Actually, at least in SketchUp, given a component (call it "Comp1.00") - or any of its instances (Comp1.01, Comp1.02, etc.) - when selecting any one of these and making it "Unique" one turns it into a new component (call it "Comp1.02_Copy1.00"). This is like a branching out from the originals a new non-twin sibling whilst still allowing new instances from that new copy. In other words, both the original and the unique copy remain "instance-able".

Cheers,

. Diego .