From Pluralpedia, the collaborative plurality dictionary
duosystem (n.)
Other formsDuoplural
Applies tosystems, system functions
CoinerCapri Suns & Gushers🍒🐙 / Plurgai

A duosystem refers to

1) The other body to one shared system/plurality. People living in a second body that feels as if it's the other half to a system.

The other body that the shared system resides in/the group of people whose home is usually the other body. One system in two bodies.

Can be two systems that share a gateway.

2) The other half to a system. Like a soulmate is the other half of a soul in mythos, the entire system is the other half to the system.

Usually has constellations (Different types of relationships between everyone). Two systems that are soul mates.

Sort of like mirror system.

* Can involve system travelling/hopping, and can be one definition, the other, or both. Can be more than two systems.