Uhhm...I think that the crusaders stuff are also upgrades though....
Besides, you can fake conflicts for sciences by using upgrades (just make them free or something for purchase, but that you can only purchase one of the two....that way you can code that by purchasing an upgrade science, you get that science, but since you can't buy the other upgrade sciecne then, you won't be able to get the other science...problem soved).
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