I am setting up a new server machine, which will host multiple django websites.
I must point out that I own (developed and are in absolute control of) all websites that will be run on the server.
I am pretty certain that ALL of the websites will be using the same version of:
No. It would probably work, but it would be a bad idea.
Firstly, it's not clear what kind of "resources" you think would be wasted. The only relevant thing is disk space, and we're talking about a few megabytes only; not even worth thinking about.
Secondly, you'd now make it impossible to upgrade any of them individually; for anything beyond a trivial upgrade, you'd need to test and release them all together, rather than just doing what you need and deploying that one on its own.