When I try to submit an answer/comment, I get a "This appears to be a duplicate" notification.

Question

Why do I get a "duplicate" response on my first answer/comment?

Answer 1

This happens occasionally, probably nothing more than accidentally double clicking the answer button.

Answer 2

It happens to me, I think I have a dodgy mouse, because I also get a duplicated set of ref tags sometimes when I only click once.
There's a setting under Mouse Properties in Windows where you can change the speed of a double click, which may help.

Answer 3

It can take up to 10 seconds before your answer is actually processed. As Marion and Gillian say: do click only once and take a coffee