MAINT PERSONNEL; DURING ACFT REPOSITIONING ON ARPT; CONFUSE SIMILAR SOUNDING ACR CALL SIGNS AND CROSS RWY; CAUSING AN SF34 ON FINAL TO BE ISSUED A GAR.

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I AND MY PAX WERE TOLD BY OUR LEAD TO TAXI ACFT X FROM GATE TO COMPANY HANGAR. MY PAX WAS THE RADIO OPERATOR AND I WAS TAXIING THE ACFT. MY PAX CALLED ZZZ GND FOR PUSHBACK AND GND CLRED US FOR TXWY. ONCE WE STARTED OUR ENGINES AND RAMP PERSONNEL WERE CLR OF TXWY; MY PAX CALLED GND FOR TAXI INSTRUCTIONS TO COMPANY HANGAR. GND INSTRUCTED US TO HOLD SHORT RWY XA RIGHT AT TXWY. MY PAX REPLIED BACK INSTRUCTIONS TO GND. WE HELD SHORT OF QUEBEC RWY XA RIGHT. AS WERE HOLDING; ANOTHER COMPANY ACFT Y WAS COMING FROM THE COMPANY HANGAR TO GATE. GND DECIDED TO CALL THEM COMPANY ONE. THERE WAS ALSO ANOTHER COMPANY ACFT (WITH A SIMILAR A/N) ACFT Z; ON GND WAITING FOR CROSSING INSTRUCTIONS. GND CALLED US AND INSTRUCTED US TO CROSS RWY XA RIGHT AFTER THE B757 AND HOLD RWY XA LEFT. PAX REPLIED BACK TAXI INSTRUCTIONS. GND CALLED US BACK AND TOLD US TO DISREGARD INSTRUCTIONS AND HOLD RWY XA RIGHT. WE HELD SHORT RWY XA RIGHT. GND CALLED COMPANY Y ABOUT 3 MINS LATER AND SAID TO HOLD SHORT RWY XA RIGHT. MY PAX REPLIED BACK AND SAID WE ARE HOLDING SHORT OF RWY XA RIGHT. GND SAID OK. THEN GND CALLED US BACK AND INSTRUCTED US TO CROSS RWY XA RIGHT/XB LEFT. I APPLIED PWR; PROCEEDING TO CROSS RWY XA RIGHT; NOTICED ACFT (SAAB) TO BE HOLDING AT END OF RWY; THEN APPEARED TO BE ON TAKEOFF ROLL. APPLIED MODERATE PWR AND CLRED RWY XA RIGHT. SUPPLEMENTAL INFO FROM ACN 521951: GND SAID CROSS RWY XA RIGHT AND XB LEFT AND THEN HOLD RWY XA RIGHT AND XB LEFT AND I REPLIED HOLD SHORT RWY XA RIGHT AND XB LEFT BUT; IT WAS TOO LATE WE ALREADY PROCEEDED CROSSING RWY XA RIGHT AND XB LEFT AND WE WERE ABOUT A QUARTER OF THE WAY IN OF THE IN OF THE RWY XA RIGHT AND XB LEFT HOLD SHORT LINE; SO AT THIS TIME WE SAW A LIGHT AT THE END OF THE XA RIGHT AND XB LEFT RWY AND REALIZED AN ACFT APPEARED TO BE AT TAKEOFF. SEEING THE LIGHTS WERE GETTING CLOSER WE PROCEEDED TO MAKE WAY FOR THE ACFT. WE THEN NOTIFIED GND THAT WE CROSSED RWY XA RIGHT AND XB LEFT. WHILE ALL THIS WAS TAKING PLACE THERE WAS A LOT CONFUSION WITH ACFT Z AND ACFT Y AND US (ACFT X). THE TWR WAS CONFUSED OF THE LOCATIONS AND NUMBERS; THAT'S WHEN TWR ASSIGNED ACFT Y COMPANY NUMBER ONE. THERE WAS A LOT OF MOVEMENT ON THE ARPT THAT DAY AND POSSIBLY GAVE US THE WRONG INSTRUCTIONS.