Two different versions of Mahabharata are available, Northern and southern recension. Both of them don't have same number of chapters and verses. For example, Sabha Parva of kumbakonam version of Mahabharata has 103 chapters, but K.M. Ganguly's translation has only 80 chapters. The same goes with the Puranas. For example, Padma Purana has two versions according to this website; Bengal version which has seven Cantos and Southern version which has five Cantos.
Now, my question is, how can we identify which is real and which is not?