The levels are cut into smaller chunks so some levels that were originally a single level become 2 different ones. On topic: The Xbox campaign of Doom 3 is very similar but there are some notable differences that give it it's own special flavor. Then to make it even better my amazon order of the MC: Collection got lost so I never even got it anyway :( Then a couple of weeks later they announced that all the Halo games are coming to PC lol. I bought an Xbox one just so that I could play all the Halo games. Getting an Xbox360 just to play one game for a couple of minutes doesn't sound like the best idea lol I got very lucky recently and found what is probably one of the only amazon sellers that still sold copies that would actually ship to where I live.
Getting actual copies of the original Xbox Doom 3 would be much harder though. You could just buy an original Xbox or even an Xbox 360 for cheap online. GeneralLotz recently live streamed all the Doom 3 and RoE Xbox levels and uploaded them to youtube. You can always watch a Let's play to see how the Xbox levels differ from the PC originals. Would it be possible to port these over to the PC version? they look different than the ones in the other Co-op mods. Actually is that other player model in the XBOX port?