IMHO a few owners have multiple teams so they can make favourable trades in one league to garner a favour in another.
Like or lump it, thats what I think
I've actually had that offered once or twice, I prefer to win as much as possible with each and every team so I haven't done it, but it probably does happen from time to time.
If that were ever offered to me I'd out the person ASAP. We don't need that type of **** in MFN.
My pet peeve, and what I try to avoid if I can (I'm actually trying to remember if I did this ever to a team here, I hope not), is when a new owner takes over a team, "cleans up the roster", and then leaves the team with 10s of millions in dead cap. When I take over a team, and do roster clean up, I try to hold on to the team at least until I can clear most of the dead cap if not all of it. That way the next owner isn't completely hammered when they take over the team.
I try to own a maximum of 3 teams because unlike some owners (Not calling out any owners with multiple teams that actually contribute to their teams and the game, I respect you guys), I actually put time and effort into my teams.