'Sister, Sister' -- Ex Co-Star Double Up ... Sentenced for Second DUI

A former "Sister, Sister" star is learning the hard way ... some things shouldn't come in pairs -- Dorien Wilson just got nailed for a second DUI.

Law enforcement sources tell us Wilson was driving in Los Angeles back in February when he was pulled over and booked for DUI. Wilson, who played Terrence Winningham on the show, was in court Friday and pled no contest to the charge.

He was sentenced to 4 days in jail and 4 years probation. He also has to have an interlock device installed in his vehicle -- not that it matters right now ... since his license has been suspended.

Wilson's previous DUI arrest was in 2009.