Problem creating distinct timers

I have an app in which there are 2 identical units that have a timer that displays elapsed time. I’m using a single file for these units since they are identical. When a user turns one of the units on, its timer is supposed to start and when they turn it off, it should then stop.
The problem I’m having is this:

If I go to one unit and turn it on, and, after 2-3 minutes, turn it off, then go to the 2nd unit, instead of displaying 0:00, it displays the 2:00+ that was on the first unit. If I go back to the first unit and turn it back on, instead of starting at the 2:00+ mark, it starts up at 3:00 or later. I’m not very familiar with the way getTimer works, but I had figured that could be set to start whenever I wanted.

If the user then selects a new module, instead of restarting at 0:00, it starts off at around 5:00 or so. It appears to be giving the time from when I started the Flash piece instead of since the beginning of the module like I thought it would.

How should I code these timers so that they can start when the user selects a module and so that they can be distinct values?