You didn't say what size mouse you are feeding, but I'll assume it is what rodentpro calls a "large adult mouse" (they don't have small or medium adult mice, so it is really just a regular adult mouse).

To answer your actual question, I don't believe it matters whether you offer one larger prey or 2 smaller ones, if the total weight of the meal is equal. However, a small rat is more than double an adult mouse on average. A weanling rat might be a more appropriate step up, if you want to go with rats.

Does your snake act hungry before his regularly scheduled feeding day? Or does your snake stay in hunting mode for a while after eating instead of going to his hide to digest?

Just guessing based on your description of the size of your BP and comparing to mine, your BP might be about ready for larger meals. However, I had some extra hoppers in the freezer so I didn't go up to 2 adult mice yet.