It's just a test system, I don't have the cable to join for parallel.
Time to get a pair of Y parallel cables.
Try the 2 in series but PWM has limitations.
Your 36Vmp will be pulled down to say 14V
@snoobler said it better than I could.
PWM controllers REQUIRE all panels to be the correct nominal voltage AND they must be in parallel NOT series.
PWM controllers effectively SHORT the panels to the battery thus forcing the panel to be the battery voltage. If you put a 24V panel on a PWM controller for a 12V battery, the panel will produce less than half the rated power.
The "shorting" of the panel to the battery via the PWM controller misses out on a lot of efficiency.
As you've seen, a 100W panels with Vmp of 17.8V have an Imp of 5.62A. On a PWM controller, the panel will not be allowed to rise above the battery voltage. Thus at peak bulk voltage of say 14.4V, you're limited to 14.4V * 5.62A = 81W out of that panel in perfect conditions.