Right that putting the pedals together creates surfaces that look like daggerboards. And there should also be less drag since they are in-line with one another. Beyond that, there might be some useful lateral resistance, but it is compromised by the fact that the lower parts of the fins are designed to twist off. So they will tend to move to a position with zero angle of attack relative to the waterflow. Tightening the tensioners on them will maybe prevent this to some extent.
I think really it's likely a toss up between any gain in lateral resistance and and the added drag of the fins.
I don't think my AI2 centerboard is nearly enough lateral resistance. I've just installed daggerboard trunks in my haka benches, and am about to experiment using them with an old mistral windsurfer centerboard. Picture below shows the haka bench side on with the dagger in place.
The leeward AMA is doing a lot of the work.