^+1. :) Yup, agree with this. For this reason I generally don't buy the exact same toy for anything. There is also the other point that when you collect exact duplicates, you're leaving less in the "pool" for other collectors to have. What I sometimes do is collect variations -- having said that, I'm not a full on serious collector of variants by any means. Most of these variants are reissues.
With G1 -- I collected G1 in the 1980s and 90s. So my G1 collection is also my childhood collection, and having had these toys for so long, a lot of these toys are just getting worn. When a reissue comes out, it gives me two main opportunities:
1) A chance to replace old toys. When I get a reissue, my original G1 toy becomes 'retired' as a display piece, whereas the reissue becomes my new play piece! Some G1 toys have been "forced" into retirement because they've become so fragile, e.g. Slog and Bristleback. I really wish they would reissue the Monster Pretenders so I can play with Monstructor again!
2) A chance to collect all the little weapons and accessories that I've lost. I used to keep a LOT of my accessories in my old S.T.A.R.S. bases... I've since lost them, and the weapons (and tech specs!) they contained. :( :( Collecting weapons separately is too time consuming and would probably cost just as much as buying the reissue in the end.
But keep in mind that often years if not decades pass between when I buy one toy, and then a reissue of it. e.g. I collected G1 Devastator in 1985... at $9 each, it was relatively easy to collect the whole set in a few months (although my friends and I had collectively completed the set before I'd done so individually -- I remember we would come to school with our different Constructicons, and assemble Devastator at lunch time. ;)). Then 26 years later I got the Encore reissue.
Also...
* Combined form of Bruticus, metal variant
* Combaticons in individual robot form, metal variant
* Combaticons in alt mode form, metal variant
* Japanese packaging MISB separate boxes
* Japanese MISB gift set
^repeat for all other variations! ;)