You can't name the timers? From the mIRC help:
Quote:

/timer[N/name] [-ceomhipr] [time] <repetitions> <interval> <command>
Activates the specified timer to perform the specified command at a specified interval, and optionally at a specified time


The previous timer shouldn't be destroyed if you use timer $+ $nick. For example, if I join, there will be a timer called timerBlake, and if you join after me, there will still be a timerBlake, as well as a timerDaveC. Let me know if I'm misunderstanding something. Thanks.