the 'old' one, so to speak, is the first part of the game and the 'new' one is the second part of the game. The game was getting too large to be downloaded in 1 file so it was split to keep the file download size reasonable for all users.
So, for all intents an purposes, install the 0.14 apk and play through that til you reach the end, then install the 0.23 apk to complete the game :)