I agree that there is value to redundancy — if you have two batteries and one fails (not improbable, I have experienced a hard failure of a
12v lithium battery while camping) you can carry on. With regard to performance benefits, you would have to do research but it is possible that in the form factor of two 100Ah lithium batteries you might find a single battery with more than 200Ah.
Not a performance benefit, but the handling of two smaller batteries might be advantageous.