DEP CTLR ISSUED A CLRNC TO THE RPTING ACFT THAT WAS FOR ANOTHER ACFT OF THE SAME COMPANY. LTSS WAS THE RESULT.

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WE WERE TOLD TO CONTACT CLT DEP AT APPROX 1000-2000 FT AGL. WHEN I SWITCHED; I CALLED 'ACR CLBING TO 8000.' THE CTLR RESPONDED WITH OUR FLT NUMBER AND THE CLRNC TO TURN R 210 DEGS; INTERCEPT THE GREAT TRANSITION; CLB TO 12000. THE CAPT AND I VERIFIED THE NEW ALT IN THE WINDOW; TURNED TO 210 DEGS AND SET UP THE INTERCEPT IN THE FMC. THE CTLR; AFTER SEVERAL MORE SECONDS OF DELAY; CAME BACK ON AND SAID 'THAT LAST CLRNC WAS FOR ACR Y' (OR CLOSE; I DON'T REMEMBER THE EXACT NUMBER). I LOOKED OUT MY WINDOW AND SAW US CONVERGING WITH A SAME COMPANY MLG THAT WAS BELOW AND SLIGHTLY BEHIND US. I CALLED DEP AND ASKED; 'DO YOU STILL WANT ACR ON A 180 DEG HDG?' HE ANSWERED AFFIRMATIVE AND NOTHING ELSE. I THEN CHANGED THE ALT BACK TO 8000 FT. THE CTLR HAD CALLED THE WRONG FLT NUMBER TO CLB; TURN AND INTERCEPT. IT PUT US ON A CONVERGING PATH WITH AN ACFT OFF 18R AT CLT. HE NEVER CORRECTED OUR CLRNC UNTIL WE ASKED ABOUT IT; AFTER SEEING A POSSIBLE CONFLICT. WE WERE AHEAD OF AND OUT-CLBING THE COMPANY MLG SO NO COLLISION WAS IMMINENT; BUT IT WAS WITHIN A 1/2 MI BOUNDARY. BOTH THE CAPT AND I VERIFIED THE CLRNC. WE ARE SURE THE CTLR MADE THE ERROR IN FLT NUMBER USAGE.