When we did our original IVF cycle we transferred 1 embryo and got 1 baby (YAY!)
When we did the FET's we only transferred 1 the first time because it was a strong embryo - it implanted but I had a miscarriage at the 6 week mark - with the 2nd we had planned on transferring 2 because they were weaker however, they failed to grow to Day 5 so we never got that far.
My suggestion would be that if 2 embryos got you 1 baby in your original IVF cycle, then I'd probably do the same thing for the FET or a fresh IVF cycle. I don't know your situation so this is based on what I would do if it were me.