Yes, and sort of..... Yes, they are separate installs.
** EDIT #1 ** if you did the download that got both versions they do install together.
** EDIT #2 ** I had a folder in mine called "32.01.01-Multiversion-Image". There is one setup file in there that installed all the versions in that package.
When you open Studio 5000 it automatically opens the last version you were using. You don't tell it to open a specific version. Anytime you open a project file it will switch to that version, assuming it is installed. When you create a new application in the version dropdown you will only see the options for the versions you have installed. So that is one way to verify what you have.
You may know that this software used to be called RSLogix 5000 for versions 1-20. Anything newer is called Studio 5000.
Let's assume for a moment we have version 20, 31, and 32. If you are in Studio 5000, say version 31, and you do a File/Open and select a version 32 project, it will automatically switch to Studio 5000 version 32. If, however, you do a File/Open and open a version 20 project then it will switch to RSLogix version 20. Likewise, if you are in RSLogix 5000 version 20 and open a version 32 project it will switch to Studio 5000 version 32. So, it is smart enough to not only switch versions but even switch applications.
But if you open Studio 5000 and do a File/New you would not be able to select version 20. You would have to open RSLogix 5000 manually. While in RSLogix 5000 if you did a File/New you would not be able to select version 31 & 32. So just some quirks to be aware of.
Oh, and you only activate once. It covers all versions currently installed or installed after activating.
OG