While it is possible to have multiple copies of mIRC open, it is not necessary for multiple connections.

The script and advice that has been given is designed for multiple connections/networks with one copy of mIRC being open.

It does not make sense, from the stand-point of system resources to have multiple copies of mIRC open in order to have multiple networks connected.

If you use the script/advice given, and you open a 2nd copy of mIRC using the same shortcut, then the same mirc.ini file will be used, and, thus, the same script(s) will be used.

If you have a reason for wanting/needing to run multiple copies of mIRC simultaneously, please tell us the reason and we'll have a better chance of coming up with a solution that works for you.