Double posts from one click on the post button have the exact same time stamp, right down to the second.
Yours is indeed a strange glitch.
This time, the error message looked different, and I got a triple post.
55 posted on Mon Dec 03 2012 19:20:39 GMT-0200
56 posted on Mon Dec 03 2012 19:21:37 GMT-0200
57 posted on Mon Dec 03 2012 19:22:38 GMT-0200
That was a single click on
http://www.freerepublic.com/focus/news/2965075/posts?page=55#55
FWIW, Adios