I have some AMT/ERTL unbuilt models too, al bought in the nineties.
I never bought two of the same kind, except in two cases: the Enterprise-A, because at the time there was no model of the Reliant and I thought I would kitbash one. Never built either one (but someday I intend to).
Also I have 2 Ktingas because the first one I built sucked. The 2nd never got out of the box.
Such modeler I am....