Ex-UFC fighter Melvin Guillard pled guilty to knocking out civilians on TWO separate occasions ... but TMZ Sports has learned the guy won't have to spend more time behind bars after the pleas.
36-year-old Guillard first ran into trouble on June 15, 2018 when the former fighter was working as a bouncer at The Ginn Mill bar in Denver, Colorado.
Cops say a man walked up to the entrance of the bar and confronted Guillard ... and that's when they say Melvin pushed the guy and socked him in the face -- knocking him unconscious.