For closeness and psychological compatibility
1.Dual
2.Activator
3.Identical
4.Mirror
5.Semi-Dual
6.Illusion
7.Beneficiary
8.Benefactor
9.Supervisee
10.Lookalike
11.Kindred
12.Supervisor
13.Contrary
14.Quasi-Identical
15.Super-Ego
16.Conflictor
Really, 5-12 are relatively close.