What machine are you using to post? I've never had a double (triple, quadruple) post off of the trusty old laptop.
I don't think it's a FreeRepublic issue, it's yours.
This is the same problem many have posted about in the last three weeks. You get the server error message repeatedly or no internet connection message. Then when you finally get back to the thread you see double or triple posts. We were talking about it this morning on the Sunday Talk Show thread. Makes me bananas. Short trip by the way.