Well, we thought maybe it was just a temporary glitch that the relister program was listing items twice.
To be fair, we gave it yet another try today and it's still happening. When we try to relist through the Relister program, it posts each item twice (only a few seconds apart.)
We liked the program but certainly don't want to pay eBay double the fees any longer.
I guess it's time to find another way to relist...