The only thing that happens if you re-freeze it is it gets a little more squishy. Nothing bad happens other than that though. But don't do it more than once or you might start getting a load of bacteria in the rat/mouse/whatever's gut cooking up.
That "squishy" is the guts deteriorating due to the deomposition process beginning.
Theresa Baker
No Legs and More
Florida, USA
"Stop being a wimpy monkey,; bare some teeth, steal some food and fling poo with the alphas. "