PSU Series and Parallel Tracking Mode, Current Limit Behavior
well it seems in PDF they already answered it. 
if you short - master to + master (the terminal outout should be + on master and - from slave) you get serial connection supply which mean if the setting on display 5V the  actual voltage will be 5*2 = 10V actual voltage.
the current it's stay the same on display or what you set on, the series current never doubling it self.

if the connection short together on same polarity (parallel) + short + and - short -. you will get same voltage but double the current. which mean if the display 5V 2A the actual output will be 5V 4A.

remember
parallel = more current.
series = more voltage
if you looking for explanation and calculation about this it's because the ohm law. the watt (power) same both series and parallel (if equal output each supply) but the difference it's resistance change when you put series (increasing the resistance) and parallel (decrease the resistance)