Not true. This isn't even hinted at in either the book or the movie, to me. Especially not the movies. They are clearly two different species of snake. The one Harry set free was a Burmese Python. The one portrayed as Nagini was, I believe, closer to a reticulated python. I'll have to watch again to verify this. Different patterns entirely, though. Therefore not the same snake. Besides, Nagini would have already been a Horcrux and closely guarded by Voldy as a pet. I'm sure he would have been cared for by a Deatheater somewhere. That's my opinion. However, it always bothered me that the snake in the Sorcerer's Stone winked. Snakes can't wink. They have no eyelids. Argh...Hollywood...geez...
