The important thing is the awareness – how to be aware.
At first, we start with one object to establish the awareness, and slowly the mind knows more objects. We don’t stick to being aware of only one object.
If the mind can see many objects, then let the mind know many objects. At first, we use only one object because we’re still not skilful how to be aware. When the awareness improves, it can naturally receive more than one object.
So, you need to allow the mind to know. But samatha practice only stays with one point of concentration. Also, the object of samatha practice is a concept. Vipassana object is nature/reality.
Depending on the yogi, some yogis can know many objects, and whichever is obvious, they’re aware of it. Some yogis have difficulty knowing many objects therefore they may start with only one object.