Battery technical question

[luvpt]

If I were to wire an Optima D31M in parallel with a D34M for a 12V trolling motor would that work OK? Would I be able to charge them on one bank and would they charge correctly or would one of them need to be on say a second stage charge when the other would still be on the first stage? It's complicated but I wound up with one D31M and one D34M instead of two D34M's like I had thought. The salesman misordered one and is going to give me the D31M at the other's price. I am going to take it if this will work, otherwise I will send it back for the D34M.