I have 2 Blue top Optima batteries that are in parallel, My current setup has a single 4 gauge wire running between both batt's, I just purchased 4 battery terminals that will allow me to run dual 1/0 wires between the batt's
Will this damage the batteries? is there a benefit from doing this?

Thanks
Bryan

It won't hurt anything, just allows for a very large amp flow.

Won't hurt a thing.

Bigger is better 99% of the time when dealing with batteries.

Current flow is like a hose.....the bigger the more flow. Just make sure to have the same sized grounds also.

So I have 2 1/0 (Pos and Neg) in parallel and 1 ea going to the starter and block coming from the battery switch

How are you hoking up the wire from the alternator? Those cables look great!!

I already have 1 cable each coming from the block and starter going to the battery switch, now I need to make a wire to go from the alternator to the batteries..... Thanks BTW

Why do you need two 1/0 cables hooking one batt to the other ?

Check at the starter, you may already have an alt wire there. I'd just run a new wire from alt to starter if that's the case.....unless you have a bat switch.