To start both (but not end both!):
- create a new chaser (e.g. name it "starter")
- add the step "command" => "Chasers" => <Name of it> => "Start"
- add the step "command" => "cue library" (or "cue list") => <name> => "Start"
- Click on the chaser name and unselect "Repeat".
- Set the duration of both "command steps" to 0|0|1 (by selecting the step, then on the right side)
If you start this chaser with the button, it will activate both.
The command-steps are very useful and mighty. Just try arround a little bit.