Are the grounds on the in/outs of the LED dimmer isolated or coupled?

I just placed an order for a large lighting array I'm building, including 18 dimmers. I'm hoping to get electrical details of the dimmers, to hopefully make the wiring as efficient as possible. Are the grounds on the in/outs isolated or coupled? I'm hoping they're coupled, so I can combine some of the ground wirings and bypass the dimmer on the return wiring from the LED strips. 

I don't have the schematic for the product on hand, but I do not believe that the input and output ground are coupled, so you will likely need to wire the LED strip ground back through the same dimmer's output ground.

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