I'm not sure what you mean by "running from the same settings".
He means sessions that use the same mirc.ini configuration file, basically. You might want to be able to run one copy of mIRC with mirc1.ini and a second copy of mIRC with mirc2.ini, but not be able to run two copies of mIRC with mirc1.ini at the same time. Unfortunately this looks to be a bit harder to do with your method (you'd have to compare $mircini from each session).
I think a built-in method of preventing multiple sessions would work best for this. Not because it's impossible to do with scripting, but because it would be useful enough, IMO, to build into the program directly.
