Either it is one vote per team, or one vote per man. If one vote per man is going to be your philosophy, then if you have a team with co-owners, they should each get a vote.
Because of this conflict, I would say one vote per team, which would mean you get 4 votes. Especially if this is a league with a fee to play.
Some better solutions are out there though.....
If you have 4 leagues that operate under the same constitution, but you can't fill all 4 leagues with owners, then you need to go to 2 or 3 leagues. Why have dual-ownership if you can avoid it?
My favorite way to handle this, would be for you to write a constitution, and that be the end of it. If you have 20 guys haggling over rules and having votes on how things run, you will spend more time on rules than playing the actual game and you will probably see people get upset and quit even before the season starts. Put a clause in the constitution that if over 50% of the participants notify you via email that if they wish for there to be redress of a specific rule, that a discussion among the whole league may be held. This gives you a safety net, but discourages people from sniping about small tweaks to rules every 5 minutes.