As jrg♦ said (pinned in main chat):

Hey folks who use "canned" comments: If you see one thats already there that expresses the same general idea, don't add another one. Thanks. :)

This has been happening a lot lately, and I'm pretty sure it's mainly because many people are not using the new review system in an entirely correct manner.

Short Version

If an appropriate comment (canned or not) has already been posted, don't add another one that says the same thing, even when reviewing low quality posts. If no (additional) comment is needed, use the "No comment needed" option.

If you see a duplicate comment--a comment that says the same thing as a previous comment, either in the same words or different words--flag the comment.

While it's not appropriate to post a duplicate comment, you can upvote the comment you agree with. That's one of the big reasons comments can be upvoted--to prevent unnecessary additional comments from existing.

Full Explanation

As an overview of how canned comments work, note that there are two main ways that comments get posted (semi-)automatically. Both are very good things...when used properly.

  1. The pro-forma comments userscript. (See this meta post for more information.)
  2. The new review system for low quality posts offers a Recommend Deletion button. (If you have enough reputation to cast delete votes on answers, it's a Delete button instead.) When you click this button, you are presented with the ability to post one of several pre-written comments, or no comment at all.

Screenshot showing "Add a comment for the author?" dialog in review

When we close posts, we choose a close reason. When we flag posts, we choose a flag reason. But choosing a comment when recommending deletion in review is not like that. Unfortunately, many users seem unaware that not posting a comment is often the proper choice. Consider:

  • Choosing to post a comment when recommending deletion doesn't do anything besides posting the comment. It is not a way of voting on what is wrong with the post. There is no counter that gets incremented every time someone posts (for example) the This is a comment, not an answer comment. Those comments just accumulate needlessly, take up users' and moderators time as they are flagged and removed, and distract from any potentially valuable subsequent comments on the same post.

  • It is OK to not post a comment when recommending deletion. That's why not posting any comment is the first option in the list of what to do.

  • If the comment you're about to post has already been posted, or something like it has been posted, don't post your comment. This is true even if the comment you're about to post is manually composed, or if it's a different kind of canned comment (i.e., a "pro-forma" comment).

  • If a comment has been posted addressing what's wrong with the post and you agree with it, consider upvoting the comment. Comments can be upvoted, and we get to upvote up to 30 comments per day.

    A comment with upvotes sends the message that it's supported by the community. In contrast, multiple comments saying the same thing sends the message that the the post was reviewed by people who weren't paying close enough attention to notice that what they're saying has already been said (whether or not that message is accurate).

    If you somehow manage to run out of comment upvotes (this has happened to me occasionally), however, you should still not post duplicate comments.

  • When reviewing "low quality posts," remember that you can post your own comments, and do not have to use the canned comments provided in the deletion dialog. If no one has posted a comment explaining what's wrong with a post, and none of the comments in the deletion dialog is exactly right for it, post your own comment instead.

    However, if your own comment says essentially the same thing as something that's already been said, it is almost never appropriate for you to post it.

    Furthermore, the canned comments often do say exactly the right thing; they cover some of the most common problems with sub-par posts.

  • Sometimes you might find your own canned comments (i.e., through the pro-forma comment user script) to be better than the comments offered in the deletion dialog. Unfortunately the pro-forma user script doesn't support review, but that's not a big problem. You can open the post up in a new tab/window, and post the appropriate pro-forma comment.

    However, that you're using your own customized pro-forma comments doesn't mean you should post a comment that says essentially the same thing as one that's already been posted.

Those guidelines should, hopefully, help clarify the full range of options that exist when reviewing low-quality posts.

If you don't see a lot of duplicate comments and are wondering if this is really a problem, the reason you're not seeing them is that many of them have already been flagged, and/or removed by moderators.

If you do see duplicate comments--which means comments conveying the same information, not just comments that have exactly the same wording--flag the duplicate (i.e., the second one). Or duplicates--unfortunately, a comment is often duplicated more than once.

  • I've flagged lots of these comments, and the vast majority--or all--of my flags have been approved and the comments removed. (I can't state with certainty that it's 100% since I have a small number of rejected comment flags, but I strongly suspect those rejected flags were unrelated flags, not flags on duplicate comments.)
  • I've been using custom flags to point out duplicate comments, because just by looking at a duplicate comment by itself, it might not be clear why it ought to be removed. No one has criticized me for this practice, but I'm not sure it's the best way; maybe flagging as not constructive would be preferable. Perhaps a moderator can weigh in on this.
  • It might feel unclear which of the duplicate comments should be kept (if they are worded differently). So I used to flag the post itself and explain this. But then a moderator told me in chat that I should instead flag one of the comments (presumably the second one). So as I understand it, that's what we're supposed to do in that situation.
  • 15
    This is sort of annoying actually: wish I had a virtual stick to hit all users that double comments. Commented Oct 9, 2012 at 8:59
  • 5
    The path of the righteous man is beset on all sides by the inequities of the selfish and the tyranny of evil men. Commented Oct 9, 2012 at 12:18
  • 12
    Kick me hard if I read a word of that^ :P
    – Mahesh
    Commented Oct 9, 2012 at 15:43
  • 2
    So... what happens if we use "Vote to Close: Dupe" and the system auto-generates a comment that is near equal to "This post is a duplicate of [blarghenflarghen]"? Or does this PSA not apply then?
    – Thomas Ward Mod
    Commented Oct 10, 2012 at 23:40
  • 3
    @LordofTime You can always manually delete the comment.
    – nanofarad
    Commented Oct 11, 2012 at 0:41
  • 2
    @LordofTime It is extremely rare for such duplicate comments to be generated. If there is already a comment containing a link to the question itself, the system will not create one. If existing comments only link to answers, the system will create a new comment linking to the question. (I believe this exhaustively describes how it works, but I haven't undertaken an extensive study, so I might be missing.) Also please note that you can vote to close and then edit the automatically generated comment, if you want it to present the link differently or include other information. Commented Oct 11, 2012 at 2:49
  • So... basically, it's OK to comment complaining about a non-answer, as long as you're the first one to comment about it? Commented Dec 6, 2012 at 6:06
  • 7
    @JamesTheAwesomeDude A more general statement would be: A comment should add something constructive. Commented Dec 7, 2012 at 6:13
  • The Android application also adds auto-comments. At least when a question is flagged as a duplicate.
    – Dan
    Commented Nov 18, 2013 at 11:45
  • If we do come across duplicate comments, would it be a good idea to flag them or something?
    – Wilf
    Commented Jul 20, 2014 at 20:28
  • 1
    @Wilf Since what you mean by "duplicate comments" is comments that say the same thing as, or something very similar to, other comments on the same post: yes. Duplicate comments should be flagged. This is addressed near the beginning of the post we are commenting on now. :) Just search this page for flag. [The other thing people sometimes mean by "duplicate comments" is comments that state a question is or may be a duplicate of another question (i.e., comments that say, "possible duplicate of..."). That second sort of "duplicate comment" should of course not be flagged 100% of the time. :)] Commented Jul 21, 2014 at 0:59
  • This is really quite annoying. I wish we could hit users who do this with a virtual stick. ;) ;) ;) Seriously, I noticed a little while back that I was doing that by mistake, and have taken steps to stop doing it both on AU and other sites. Thanks for the reminder!
    – anonymous2
    Commented Aug 31, 2018 at 11:22
  • Some parts of the announcement are a bit contradictory. Compare (emphases mine): “If you see one that’s already there that expresses the same general idea, don't add another one.” with “…don't post your comment (…) if it's a different kind of canned comment (i.e., a "pro-forma" comment).” So when an answer contains a link and someone posts the “link-only answer” comment but it turns out it’s just a pastebin link of someone having the same problem, should I still post the correct (canned) comment?
    – Melebius
    Commented Sep 19, 2018 at 7:45
  • 1
    @Melebius I don't see any contradiction. You over-edited your second quote so severely you changed its meaning. What it says is: "If the comment you're about to post has already been posted, or something like it has been posted, don't post your comment. This is true even if the comment you're about to post is manually composed, or if it's a different kind of canned comment" IOW, you shouldn't post a canned comment that means the same thing as a different canned comment already posted. If your canned comment says something that HASN'T already been said, then of course post it.
    – FeRD
    Commented Sep 27, 2018 at 5:42

1 Answer 1


If I see a comment that seems to cover what I want to say I try to make it a practice to just upvote that comment and move on. This seems the logical approach to me.

I seldom go backwards so it would be rare for me to revisit a question (that I didn't answer) and notice an auto-generated comment so I won't touch that aspect. I try to clean up my own comments when it becomes clear they aren't relevant or if they seem to chatty so as not to leave a mess. (Thanks to @Seth for kindly nudging me in the right direction on that.)

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