ATCT TWR CTLR BECAME CONFUSED WITH THE SAME COMPANY SIMILAR SOUNDING CALL SIGNS AND TAXIED RPTR'S ATR42 INTO POS ON THE WRONG PARALLEL RWY TO HOLD WITH LNDG TFC ON FINAL. THE CTLR GAVE A GAR TO THE ACFT ON FINAL AFTER REALIZING HIS MISTAKE.

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WE WERE READYING FOR TKOF FROM RWY 31L WHEN TURNED OVER TO THE TWR FREQ. THE LCL CTLR EITHER SPOKE WITH A THICK ACCENT; OR HIS RADIO WAS POOR; OR BOTH. AFTER A B747 ARR; WE WERE CLRED 'INTO POS AND HOLD' (OR SO WE THOUGHT). IT SOUNDED AS IF THE FIRST PART OF EACH XMISSION FROM THE TWR WAS EITHER CUT OFF; OR MUFFLED. THERE WAS ANOTHER ACFT ON FINAL AND CLRED TO LAND ON THE SAME RWY; BUT THIS WAS NORMAL PRACTICE AT THIS ARPT. AFTER BEING IN POS FOR A SHORT TIME; AND NOT GETTING TKOF CLRNC; THE PLT OF AN ARRIVING ACFT CALLED TO VERIFY THAT HE WAS IN FACT CLRED TO LAND ON THE SAME RWY. 3 SEPARATE TIMES THE CTLR STATED TO HIM THAT HE WAS 'CLRED TO LAND.' THE OTHER PLT REMARKED THAT THERE WAS AN ACFT ON THE RWY (OURS) AND THE CTLR THEN INSTRUCTED HIM TO GAR. DURING THIS TIME; THE SAME CTLR WAS WORKING TFC ON THE PARALLEL RWY. AS IT TURNED OUT; THE CLRNC INTO POS WAS MEANT FOR THE DEPARTING TFC ON THE OTHER RWY. ALTHOUGH MY FO READ BACK THE CLRNC; IT SEEMED THE CTLR DID NOT LOOK OUT THE WINDOW TO VERIFY WHO WAS GOING WHERE. THE OTHER DEP WAS ANOTHER OF OUR COMPANY'S AND HAD A FLT NUMBER OF X WHILE OURS WAS Y. THIS WAS AT A LARGE ARPT WHERE IT WAS NOT POSSIBLE TO SEE THE OTHER ACFT. BEFORE ISSUING A TKOF CLRNC TO US; THE TWR CTLR INFORMED US THAT WE TOOK A CLRNC THAT WAS INTENDED FOR ANOTHER ACFT 'WITH A SIMILAR SOUNDING CALL SIGN.' IF THE CTLR HAD MADE US AWARE THAT ANOTHER ACFT WAS ON THE SAME FREQ WITH A NEARLY IDENTICAL CALL SIGN; WE WOULD HAVE QUESTIONED THE CLRNC; BUT AT THE TIME WE THOUGHT THAT WE WERE ALONE.