### Yes, multiple omnipotent Gods can coexist.

The OP says:

> Is there a way to make the contradiction disappear? I'm not too picky about the definition of "omnipotent" - I'll be okay with a system that puts some kind of (tiny) restriction on their powers,

### Here is that tiny restriction: No God can harm another God or diminish the power of another God, or diminish the knowledge of another God. Their omnipotence applies only to the universe, not to each other.

This implies that anything a God can do, another God can undo, perfectly. One God can make our Galaxy vanish: Another can restore it with a snap of their fingers without an atom or photon out of place. She does not have to be wise or smart, just wish it to be so.

**What happens if they oppose each other?**

If they squabble; they can both sit there and do/undo each other's work for eternity, a cosmic version of the children's squabble ***Yes it is! / No it isn't!***

Such is the nature of being a God, they know this from experience, and it fits with being omnipotent. If they want something done, the ***must*** agree upon it.

Such an agreement could be a physical field (these billion galaxies are mine, those billion are yours), or it could be a theoretical division (How about I do the insects, and you do the fish, and John does the land animals, and this time Mark does the solar system?)

However they come to an agreement, the ***only*** way for a God to build something that won't be instantly vanished is to please the other Gods, or at least be tolerated by them (perhaps in exchange for their own tolerance of their creations). Their only options are agreement or stalemate, and stalemate is boring. 

I imagine a council of them setting rules about creation that they then adhere to, each in their own self-interest of having a little fun in some corner of the universe without the other kids kicking over the sand castle they built.