DURING THE TKOF ROLL AT A NFCT FIELD; A CESSNA PLT DISCOVERED THAT HE HAD ACCEPTED THE TKOF CLRNC OF AN ACFT WITH A SIMILAR SOUNDING CALL SIGN. NO CONFLICT RESULTED.

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I WAS #2 FOR TKOF ON RWY 15 AT MY HOME BASE; MTN. THE TWR CTLRS OFTEN ISSUE NON-STANDARD INSTRUCTIONS TO MOVE TFC. MTN IS NOT BUSY; BUT HAS A MIX OF STUDENTS; BUSINESS JETS; AND MIL C130'S; A10'S. A HAWKER LANDED; THERE WAS AN ON-FIELD EMER DISPATCHING 6 EMER VEHICLES PAST THE 2 OF US WAITING FOR TKOF (BOTH HAD TOLD TWR WE WERE READY AND WERE TOLD TO HOLD SHORT). TWR HAD PLANE ON FINAL GAR DUE TO EMER VEHICLES; THEN ASKED CESSNA IN FRONT OF ME IF HE COULD 'TAKE IT ON THE ROLL; AN IMMEDIATE DEP.' HE DEPARTED; I MOVED UP TO HOLD LINE; A PLANE LANDED; THEN I HEARD THE TWR ASK 'XAB; CAN YOU TAKE IT ON THE ROLL IMMEDIATE?' I RESPONDED 'XAB AFFIRMATIVE.' I HEARD 'AB CLRED IMMEDIATE TKOF; TFC ON SHORT FINAL; R DOWNWIND DEP APPROVED.' BY NOW I WAS ROLLING; CHKING COCKPIT; AND LINING UP ON RWY 15. AS I GOT TO FULL PWR; I SAW ANOTHER CESSNA HALFWAY DOWN THE RWY LIFTING OFF. AT FIRST I THOUGHT THE PREVIOUS ARR DID A LONG TOUCH AND GO; BUT QUICKLY REALIZED IT WAS ANOTHER DEP. I THINK THE CESSNA AHEAD OF ME WAS 'ZHB' WE STEPPED ON EACH OTHER REPLYING TO THE TWR; THEN BOTH TOOK ROLLING TKOFS ASSUMING WE HAD BEEN CLRED. WE WERE CLOSER THAN NORMAL; ABOUT 'OSHKOSH CLOSE.' NO PROB. UNDERLYING CAUSE WAS MY RUSH TO DEPART; AND HEARING WHAT I WANTED TO HEAR. SECONDARY CAUSE WAS TWR'S USE OF NON-STANDARD CLRNCS AND TERMINOLOGY; (FAILURE TO CLARIFY HE WAS TALKING ALTERNATELY TO 2 PLANES WITH SIMILAR CALL SIGNS). I DID NOT SEEK TO CLARIFY SIT WITH TWR CTLR DUE TO RECOGNIZING HIS VOICE. HE HAS AN ATTITUDE MOST OF THE TIME. SURE ENOUGH; 4 HRS LATER ON RETURN I GOT AN EARFUL; NOT ABOUT THIS INCIDENT; BUT ABOUT WHETHER I'D CALLED IN 'W' OR 'NW' OF THE ARPT.