... IF you only use one mirc.exe then that is just fine.
use only one mirc.exe and only run multiple instances using the "-i" switch on the command line (for your own usage), or mirc.inis in the user default application location (for multiple users /multiple accounts). Installing multiple mirc.exe just to run different profiles leads to configuration management problems - and potential conflicts if both .exes want to access the same file due to a conflict in the profiles.
After all, you don't in install MS Word twice, just because different users want to use a different normal.dotx!
Yes, I know it can be done - but it doesn't mean it should be done - and people who manage multiple users should understand how to install and run multiple user programs. You mention helping other users - what can be better than helping them to learn how to manage their access to programs in an efficient manner, and learning about secure implementation of both applications and personal configuration files.
In terms of being simple - nothing is simpler then a quick edit to the program shortcut (or copy thereof) to add the "-i" parameter. Certainly easier than multiple installs and managing the multiple exe files!
See "Command Line" in the help file and have a little experiment for yourself.