You have the option to run as many timers as you'd like simultaneously. To add another timer, click on the clock area of the timer (top right-hand corner) and click the ‘+’ sign.
You may any timers at any time by clicking the gray pause button. Click the green play button to begin the timer. Click the blue check button to save and create a new time entry. Activating an additional timer will automatically pause any active timers so you don't inadvertently track time to the wrong contact or matter.