Why would you want Shuttle 3.8.5 and 4.0.1 in the same install?
Answer is no you cannot.
No, I did'nt mean that,
I do not want shuttle fleet 3.8.5 & fleet 4.0.1 at same time.
I just want Atlantis 3.8.5 (i do not no what is this, the name i saw at some addons at orbit hangar, I think its shuttle fleet 3.8.5)
I just want to play that playback.
If you need 3.8.5 for that playback, you can just make another Orbiter "install." Just unzip the folder into another location and put it there.
There's nothing stopping you from doing that, and in fact that's a good idea.
Yeah! Its a good Idea, and I did it Before seeing your post, BUT THANKS.