How big are they?
There is a thread here somewhere with detailed picture but it needs to be dug up.
Seems you may be right that the larger one is the male. In my experience though this may not be spawning behavior, you mentioned that you remover the driftwood which opens up lines of sight between the aro and the bass. When I had a silver with peacock bass they did the same thingJust eye balling they look around 12" 13". To me its seems like the larger one is a male because its more colorful and territorial. The smaller bass is non aggressive and just follows the larger bass around.