DMX That OTHER Earl Simmons Better Pay My Child Support (VIDEO)

DMX has a touching message for the poor guy who was mistaken for him in a paternity case -- and that message is ... WHERE'S THE CHECK, FOOL??

We got X in NYC, fresh off his jail sentence for a different child support case, and asked him about the story we broke -- an Earl Simmons in Massachusetts got a demand for a paternity test from DMX's baby mama in Florida.

Considering DMX knows the baby mama, and doesn't dispute the kids are his ... you'd expect him to clear up the confusion and let the guy off the hook, right?