I don't see how you can have too much oxygen...

But all of that is overkill. You don't even need to have ONE unless you have fish that need high-oxygen waters.

 

i want to dubble up on my gear in case of a fauiler somewhere

 

Even if one fails... which is unlikely, you are still fine (unless of course you have a power outage). Like I said, air stones/pumps are not needed.

 

It's not the amount of equipments that would amount to the level of oxygen. I wonder how those equipments are utilized for the surface movements responsible for the air exchange. If the filters and pumps are producing vigorous surface movements, then you don't need to set up the airpumps for that tank. If space is not an issue, get a few more tanks for quarantine and backups and use the airpumps to connect with sponge filters for the new tanks.

 

Water can only hold so much oxygen. Moving the water around just helps the air exchange so that the oxygen level in the water can get back to it's near max. Here's a link that explains it better than I can. But I agree it sounds like you have a little overkill on the water movement.

Water Quality

 

The air stones don't add oxygen directly to the water how you might think it does. The residence time of the bubbles is simply too low to facilitate much gas exchange across the tiny surface of the bubble. What air stones do is agitate the surface, increasing its area and that larger area helps to oxygenate the waters more than they otherwise would be able to.

That being said, your two filters should be more than capable of disturbing the surface on all on their own without any other help.