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Jahlil Okafor fought at least 2 PEOPLE during his violent night out in Boston last week ... and TMZ Sports has the new footage which shows the NBA star on the attack.

Witnesses at the scene tell TMZ Sports the new footage takes place AFTER the first fight on Nov. 25th ... a little further down the street.

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In the video, you can see the 6'11" rookie trading insults with a heckler -- while people in Okafor's crew tried desperately to hold him back and walk him away from the situation.

The Philadelphia 76ers star breaks away and throws punches at the heckler ... and a melee ensues.

You can see a man gets knocked out cold in the street -- suffering gashes on his face -- but it's hard to tell who threw the punch.

A witness tells us it was Okafor who "hit the guy with a haymaker."

Boston PD is investigating the incident with officials telling us charges are likely to be filed.