and then refresh the page through the browser or F5, the merit will be sent again. Although if you do this without a short break, then a window will pop up warning you about merit sending to the post twice.
It will only proceed once you click the resend button, so it still the user's fault if he will proceed.
While theymos have solution something like this "remerit" but it's for the clicking the merit button twice.
Alright, you now can't merit the same post with the same amount within 60 seconds.
So I don't think we will see a solution or kind of fix for this since this is not a big problem.