POTENTIAL CONFLICT AS ACR STARTED TKOF FROM THRESHOLD WHILE SMA ACFT STARTED TKOF FROM INTERSECTION FURTHER DOWN THE SAME RWY. ACR SAW SMA AND ABORTED TKOF EASILY. PLT DEVIATION AND OR OPERATIONAL ERROR.

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WE WERE CLRED INTO POS ON RWY 31L AT MDW. THERE WAS AN SMA Y ABOUT 1000' AHEAD OF US ON A TXWY TO OUR LEFT. TWR CLRED EITHER US OR SMA Y FOR TKOF. OUR CALL NUMBER WAS GEG AND SMA Y'S WAS GFG (I THINK). I'M NOT SURE WHETHER SMA Y OR I RECEIVED THE TKOF CLRNC. TWR'S XMISSION WERE BROKEN. WE ADDED THE PWR AND STARTED TO ROLL; THEN SMA Y ROLLED ONTO THE RWY AHEAD OF US AND TOOK OFF; SO WE STOPPED AND TAXIED BACK. WE AGAIN WERE CLRED FOR TKOF AND LEFT W/O INCIDENT. THE PROB HERE IS; WE THINK WE RECEIVED THE TKOF CLRNC AND WE READ BACK THE TKOF CLRNC INCLUDING OUR CALL SIGN AND TWR DID NOT CORRECT US. MAYBE SMA Y TOOK OUR CLRNC OR WE TOOK HIS; I DON'T KNOW. OUR RADIO TECHNIQUES WERE PERFECT. THIS WAS JUST A COMBINATION OF ERRORS BY ATC; US OR SMA PLT. HUMAN ERRORS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR HAS NOT HEARD ANY MORE ABOUT INCIDENT FROM FAA AND DOES NOT BELIEVE THERE WAS ANY RPTS OR COMPLAINTS FILED BY ANY OF THE PARTIES INVOLVED. STILL NOT SURE IF SMA ACCEPTED TKOF CLRNC MEANT FOR ACR OR VICE VERSA. ACR WAS AT SMA 5 O'CLOCK POS WHEN CLRNC ISSUED. SMA Y WAS ON N-S TXWY. ACR X ONLY MOVED ABOUT 100' ON RWY WHEN THEY STOPPED AND TURNED AROUND. TWR DID NOT SAY ANYTHING TO EITHER ACFT REF TKOF W/O CLRNC.