It never happened to me, and I have a long history of double, triple and even sextuple posting.
3 double posts in less than 3 pages http://www.cartographersguild.com/sh...ad.php?t=28977
6 messages in a row here : http://www.cartographersguild.com/sh...t=27782&page=4
I would have had 10 but someone interrupted me.