There are 2 possible solutions. The first is using portable mode. Portable mode means a separate OBS installation in a different folder that saves its configuration there instead of the default directory in the user's appdata directory. How to use portable mode, see this guide:
https://obsproject.com/forum/resources/obs-and-obs-studio-portable-mode-on-windows.359/
The second is easier, because it lets keep your preferences in the default directoy. You can make OBS start with a given profile and with a given scene collection, and with a given scene. There are 3 command line options for this: --collection "name c" --profile "name p" --scene "name s"
Make yourself two different desktop shortcuts for OBS. In one shortcut, you give the command line options to activate your profile, collection and scene for YT channel 1, and in the other shortcut you give the commandline options to activate the same for channel 2.
This way, you still have everything within reach of one OBS installation, but the switching is done by starting OBS with the respective shortcut - just as you would if you use portable mode.