It wont detect non-active clones, unless it's installed inside one of them, or you specify the path by using the '-o' command line parameter. Active clones will be detected as lone as they meet the criteria above.
In all cases where auto-detection fails, you can specify the path to the game using '-o', and from there it will detect which game it is (by looking for Oblivion.exe or Skyrim.exe, etc).