I started two TBH hives this spring. One hive is over half full of comb and has consistently had more bees coming and going. The second hive is about a third full of comb and the combs are not as large as the first.

At first I thought maybe the queen was gone in the second hive and so I ordered a new one that just arrived. Before I added the queen and to be very sure I just inspected all the combs in the second hive and they all look like they are filled with honey. From about 1/2 to 3/4 full. I don't see any eggs or brood. There seems to be a fair number of bees though. A lot more than I would think with no brood.

Is it possible it has no queen and has been 'taken over' by the first hive for honey combs only?

The hives are in close proximity. Their entrances are about 4 feet apart.

If this is the case, should I add a new queen to the second hive?

I am perplexed, yet fascinated by this situation. At this point I could use some sound advice.