Nope. All is normal here.
I've noticed a few of my comments doubling up. Anyone else been having that problem?
Uhhhh yah i am normal to!!!!
(That's my story and I am sticking to it!)
It has happened to me before, but only when I've done what Danae has explained in her answer.
There is a delay when you click on Post or Answer, so you could be clicking on the button twice because of the lag and that will make it post twice.