[Quilmeño89]

I think it is worth analyzing each case. I drew buildings both ways.
In Argentina it is very common for one tower to be built first and one or two years later, the other. In those cases, it seems better to me that they go separately (they also have independent accesses, different names or individual entries in sites like Emporis).
Some time ago I made a request for a hotel with two towers, but with shared access and one of the mods suggested dividing it into two entries. I said no, since they shared the entrance.
On the other hand, I requested a building divided into two entries, because its towers and their bases will be built separately, in different years, and they will have separate entrances. But the mod said they should go together and I have to say that, by design, it was better that way.