What do you mean flawless replicas? You mean someone made these armors from scratch even though they're already ingame? If I recall correctly, FO3 didn't have any pre-order bonus items so why would you recreate anything that's already in the game?
Uh, the NV bonus items are quite obviously not ingame in FO3. However, the pre-order armours are just slightly modified versions of several regular FO3 armours, so someone did the same alterations.
http://www.fallout3nexus.com/downloads/file.php?id=13688, preorder items http://fallout.wikia.com/wiki/File:Fnv-caravanpack.jpg http://fallout.wikia.com/wiki/File:Fnv-classicpack.jpg http://fallout.wikia.com/wiki/File:Fnv-mercenarypack.jpg
If NV includes the regular metal, leather or armoured vault suit meshes it'd be perfectly legit to make a "Faux Preorders" mod as these are just altered versions of those meshes.