SF340 CAPT STARTED TO CROSS RWY AFTER HOLDING WHEN MISTAKENLY RESPONDING TO ANOTHER COMPANY ACFT SIMILAR SOUNDING CALLSIGN. FO CAUGHT THE ERROR.

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AFTER COMPLETING OUR FLIGHTS FOR THE DAY; WE WERE TAXIING FROM THE PAX TERMINAL TO OUR COMPANY'S HANGAR ON OPPOSITE SIDE OF FIELD. IT IS NECESSARY TO CROSS THE ACTIVE RWYS TO ACCOMPLISH THIS. WE WERE TOLD TO HOLD SHORT OF RWY 06L; WHICH WE DID AT DELTA INTXN. A COMPANY TWIN OTTER WAS IN POSITION ON RWY 06L AHEAD AND SLIGHTLY L OF US. AT THE SAME TIME; ANOTHER COMPANY DASH 8 WITH SIMILAR CALLSIGN TO OURS WAS ACROSS THE 2 RWYS ATTEMPTING TO CROSS FROM COMPANY HANGAR TO THE TERMINAL OPPOSITE DIRECTION. GND CTL CLRED THE COMPANY DASH 8 TO CROSS BOTH RWYS. FOR SOME REASON; I THOUGHT IT WAS OUR ACFT THAT HAD BEEN CLRED TO CROSS. I ADDED PWR TO CROSS; BUT LUCKILY THE FO REALIZED MY MISTAKE. I ABORTED THE TAXI IMMEDIATELY; BUT HAD ALREADY CROSSED THE HOLD LINE. WE DIDN'T INFORM ATC WE WERE SLIGHTLY OVER THE HOLD LINE. AT THIS POINT; ATC CLRED THE TWIN OTTER FOR TAKEOFF ON RWY 6L. ALSO AT THIS TIME; OUR COMPANY DASH 8 WAS CROSSING BOTH PARALLEL RWYS IN OPPOSITE DIRECTION ON A TXWY W OF OUR POSITION. AT THIS POINT; ATC CLRED US TO CROSS BOTH PARALLEL RWYS. THERE WAS NO CONFLICT TO OUR KNOWLEDGE; AND ATC NEVER MENTIONED ANYTHING OUT OF THE ORDINARY.