CRJ-200 DEP FROM DFW ENTERS RWY BASED ON CLRNC INTENDED FOR ANOTHER COMPANY ACFT.

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TAXI OUT TO RWY 35L IN DFW VIA TXWY K AND HOLD SHORT AT EQ. MULTIPLE ACFT WAITING FOR DEP AND AN ACR Z MD80 WAS CLRED POS; THEN TOOK OFF IN FRONT OF US ON EQ. AT THIS TIME; WE WERE #1 AT EQ AND ANOTHER ACR XX RJ WAS #1 AT EP; TO OUR L. WE WERE CLRED INTO POS AND HOLD AND FO MADE THE STANDARD CALL OF 'TAXI INTO POS AND HOLD RWY 35L; ACFT X ABC.' THEN THE CTLR CLRED SEVERAL ACFT TO CROSS RWY 35L DOWNFIELD. AFTER ALL ACFT CLRED; THE TWR SAID 'ACFT Y; CBA; CLRED FOR TKOF.' I CALLED FOR TKOF CHK BELOW THE LINE; THEN LOOKING AT FO; WE BOTH AGREED WE WANTED TO VERIFY THE CTLR SAID 'CBA' AND TO VERIFY THE CTLR MEANT TO SAY 'ABC;' BUT BY THIS TIME; THE CTLR WAS ASKING US IF WE WERE 'ABC.' WE STATED YES; 'ABC.' THEN THE TWR CTLR ASKED WHERE 'CBA' WAS. 'CBA' STATED THEY WERE HOLDING SHORT OF RWY 35L AT EP. THIS WAS THE FIRST TIME THAT I OR FO EVER KNEW THAT A 'CBA' WAS ON THE RADIO AND HAD NO IDEA THAT ANY ACFT; COMPANY Y; Z; XX; ETC; MIGHT HAVE THE SAME NUMBERS WITHIN THEIR CALL SIGN. AFTER CLARIFICATION; THE TWR CLRED US; 'ABC;' FOR TKOF AND MADE A COMMENT TO US WHEN DIRECTING US TO CONTACT DEP TO 'LISTEN UP TO CALL SIGN BECAUSE THERE'S A 'CBA' BEHIND YOU.' MY FO CLRLY STATED OUR CALL SIGN BOTH TIMES WHEN RESPONDING TO TWR AND ONLY AFTER THE TWR SAID 'CBA; CLRED FOR TKOF;' DID WE HEAR ANY NUMBER 'CBA.' AT THIS POINT WE WERE GOING TO QUERY THE CTLR ABOUT 'ABC; 'BUT THE TWR CTLR BEAT US TO THE MIKE ABOUT READBACK OF 'ABC.' THE CTLR DID NOT CATCH OUR READBACK OF 'ABC; CBA' BECAUSE I BELIEVE HE WAS BUSY XING ACFT DOWNFIELD OR THE XMISSION WAS STEPPED ON AND NO ONE WAS AWARE OF IT. BY THE FIRST TIME WE HEARD 'CBA' SAID; WE WERE ON THE RWY ABOUT TO ASK THE TWR THAT HE MEANT 'ABC.' AGAIN; MY FO WAS VERY CLR ABOUT SAYING 'ABC' AND UNTIL THE CTLR CLRED 'CBA' FOR TKOF I HAD NO REASON FOR CONCERN.