Allow to install two versions of a game side-by-side

[xan2622]

There is a game I like much (http://www.desura.com/games/openra) and it comes with two versions: Release and Playtest.

After installing the Release version, I also wanted to install Playtest but instead of installing it side-by-side, Desura removed Release and replaced it by Playtest. ;-/

Is there a way to have both?