I am a law school graduate. WHat I offer is mere information, not to be construed as forming an attorney client relationship.
You have a written agreement stating the $ in each account is yours? Or at least a portion of it? THat is VERY VERY SMART.
Now, it would be better if you took him to small claims (if the money in both accounts is less than the total cap allowed by the state). If you want to bring both actions together, may I suggest you file them separately on the same day though and bring both to court. The judge may decide to do away with both for interests sake. You get away with a lot more in small claims court than in other more heavier civil suit situations.
If you bring them as separate suits, you may or may not be barred. They ARE separate accounts and thus separate actions. BUT if they are under one written agreement, it may be different.
Okay, light bulb. Ask the court clerk what the practice of that court is: file separate causes of action on one day and ask the court to consolidate them into one action for court efficiency OR file under one claim and have the court resolve both.
If it is one written instrument, I would attach both to one suit.
I.e. this written agreements covers my funds in
1) account A AND
2) account B.
Hope this helps.