It is completely understandable that inexperienced users are not completely aware of how to handle dupes. It is also understandable that a friendly-meaning person posts an answer, (only) linking to another answer, assuming he or she is helpful. Nothing to add, nothing to elaborate, just a link.
That is what happened here. The question should (one would say of course) have been marked as a dupe if he thinks the linked answer suits the question. I commented the poster he should have done that instead.
I was therefore quite flabbergasted that (up)voting started on the answer, which made it clear to me that not only inexperienced answerers were involved, but voters also need to be aware of the fact that we vote on good answers, not on being seemingly "nice". Nothing wrong with being nice, but that's not what we vote for.
Please don't start voting on an answer that only points to another, good and already existing answer on AU. It is encouraging unfruitful behaviour. Vote on the original answer instead if you think it's worth your vote.