Given that the cold laser is connected to Out 1 directly, and not via the boost (should not be using a boosted output), this leaves Out 2 open and unused. The cold laser requires a negative offset to function.
If Out 2's output matches Out 1 (not inverse+sync), then I see no reason why you can not connect a second laser to Out 2.
The preset Spooky Cold Laser - JW already has Out 2 setup properly. You will note that the offset is -100 for both outputs, both are set to use square waves, each at 20v.
By default both outputs get the same frequency. Using standard Out 2 modifiers, you can generate a different frequency on Out 2 if you wish.
You can modify Out 2 frequencies using the Out 2 = (Out 1 x #) + # -  Hz line. If you wanted to use the scoon effect on the second laser, have it set as follows:
Out 2 = (Out 1 x 1) + 1 - [unchecked] Hz
You can use the KHZ frequencies if you wish. What I have noted though is that the higher the frequency, the dimmer the laser output gets being rapidly turned on and off. Due to this, I tend to stick to the lower frequencies myself.
For more details, please check the link: