If you are asking whether you should give the refrozen to the one that won't eat easily, I would say no.
The reason being, you want to see if "leaving the prey" works. If you use a re-frozen rat and the snake does not eat, you can't be sure why.
Did it not eat because...well, just because.
Or did it not eat because that re-frozen rat has turned to mush inside, possibly?
Until you figure out what is going on, I would try to make this as straight forward as you can.
