is it possible to run 2 instances of LOL...

[Hugh Manatee]

At the same time with no ill effects? I kinda wish I could play skirmishes or the campaign while watch for action, but I just want to make sue that won't break my game or the install.

[PhilD]

I sometimes run 2 instances myself - one logged into the lobby, and one mercilessly stomping on the AI using the "one unit" rule. Works fine. What you can't do is log both into the lobby and talk to yourself.