Yup Omar says it quite well.
To help drive the point home even more here’s a body metaphor: “An armature can have multiple arms (i.e. bones), but an arm cannot have multiple armatures”
Just like in real life an arm can’t have multiple bodies, but a body can have more than one arm. Usually you see two of these on people, but I’ll give you a hand if you find someone with three (pun intended)