Second entrance on south side

My bees seem to have created a small second entrance on the Southside near the top box. I am wondering if I should block this off for them or not. We did have flooding in paddock last spring that came within 10mm of lower entrance. Wondering if they wanted this upper exit/entry.

I am not a fan of multiple entrances, just extra places for the guards to defend. I would vote to seal it off.