Look at this post
How to efficiently partition a single Windows-Ubuntu dual boot disk?
I'm just wondering, what happened here… Could I make the same?
No answer on that post has a bounty awarded to it yet. There's just an ongoing bounty on it, but it was started by another user, and not the one who wrote those posts. This is perfectly fine - both answering your own questions, and offering bounties on existing posts by other users are OK. Even if Fabby were to offer a bounty on his question, he wouldn't be able to award it to his own answer.
I'm the idiot who posted that question and all the answers to that question as well.
Depending on what you're exactly asking:
- Is it allowed to write your own question and answer it yourself?
- Yes that's allowed!
- Is it allowed to put a bounty on a question after it has been answered?
- Yes, that's allowed!
- Is it allowed to write multiple answers to the same question?
- Yes, only asked a few days ago...
- Is it allowed to upvote that question and all its answers?
- Yes, Please! Go ahead!
The bounty was awarded by another user. And yes, can totally happen if it so happens that the user felt it was needed.
I've often awarded bounties to other folks questions, though I've never done so for a QA pair, nor received a pair. But it makes total sense as a way to get attention to a question (then find the OP posted an awesome answer) or to reward a useful answer.