Running multiple game instances

What would be good solution to run multiple game instances where game does not allow doing it, without installing same game to another WINEPREFIX?
I’m trying to run multiple instances of San Andreas Multiplayer (SAMP). First thing that I tried: Create new game (new WINEPREFIX) and make symbolic link to the game directory that is in another WINEPREFIX. It worked, but not perfectly, had some issues with text rendering.
Copying game directory from one WINEPREFIX to another does not resolve previously mentioned issue, but reinstalling SAMP into copied game directory solved that issue, but now I cannot run two instances of SAMP, even though they’re launched from different WINEPREFIX. What else can I try?

I take it your goal here is not around prefixes, but having multiple copies of chunky game data.

In this modern age, the way most windows games store config and save data is a combination of registry entries and files under your Users directory. This will make the use of different prefixes a requirement.

You could try narrowing down the symlinks to game data files only, rather than directories - anything that does not change and is read-only is a good bet - like data files, EXEs. If you symlink anything else like cache directories, it’s going to end up a bit screwy.