YVK -- The transaction log does show that you were billed twice. The first was at 18:49 on 23rd Feb 2012 for 25.00 USD and then again at 10:09 on 4th Mar 2012 for 25.00 USD. Your account shows that you are are paid Site Supporter until 02-25-2014, so at least you were given credit for the second charge.
I don't know why that happened, but I'll look into to and see if I can figure anything out.
I'm not sure I have the appropriate level of access needed to refund the second charge to you, but if that's what you want (instead of just being paid up for 2-years), let us know and I'm sure we can figure out how to do that when ToddG gets back into town.
Sorry for the inconvenience.