WHILE ENCOUNTERING INFLT ICING; AN SF340 FLT CREW EXPERIENCES AN ALT EXCURSION AFTER TAKING A CLRNC FOR CLB MEANT FOR ANOTHER FLT WHILE 13 MI E OF HUO; NY.

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WE DEPARTED LGA; LEVELED AT 12000 FT. WE WERE FILED FOR 16000 FT. WE WERE PICKING UP LIGHT TO MODERATE ICE. WE REQUESTED HIGHER TO GET OUT OF THE ICE. ABOUT 5 MINS LATER; BOTH CAPT AND FO HEARD THE CTLR CLR US UP TO 16000 FT. WE ANSWERED THE CALL; SET THE ALT; VERIFIED IT AND STARTED TO CLB. AS WE NEARED 13000 FT; ZNY ASKED US OUR ALT. WE SAID OUT OF 13000 FT FOR 16000 FT. ZNY SAID 'YOU TOOK ANOTHER ACFT'S CLB;' AND TO LEVEL AT 14000 FT. WE ACKNOWLEDGED AND LEVELED OFF AT 14000 FT. AS FAR AS I KNOW; NO CONFLICT EVER OCCURRED. I SEE NO WAY TO AVOID THIS KIND OF ALTDEV. BOTH CREW MEMBERS WERE TIRED. WE HAD FLOWN NIGHTS ALL MONTH. WE WERE SCHEDULED FOR 9 HRS OFF. HOWEVER; THE HOTEL VAN WAS LATE AND BY THE TIME WE GOT TO THE HOTEL; WE ONLY HAD 8 1/2 HRS. THE HOTEL VAN RAN EVERY 1/2 HR; SO WE WERE ONLY 8 HRS IN THE HOTEL. SINCE WE BOTH WERE USED TO NIGHTS; WE ONLY GOT 4-5 HRS SLEEP. SINCE OUR COMPANY SAYS THE FAA SAYS THIS IS PROPER REST AND IF YOU CALL OFF DUE TO NOT BEING PROPERLY RESTED; THEY WILL GIVE YOU DAYS OFF AND POSSIBLY TERMINATE YOU. PLTS WILL FLY TIRED! IF WE WERE RESTED; THE ERROR STILL MAY HAVE HAPPENED. WE HAVE FLOWN THE RTE MANY TIMES AND THE CLB WAS GIVEN EARLIER THAN USUAL. HOWEVER; WE HAD ASKED FOR HIGHER DUE TO THE ICING CONDITIONS; SO GETTING THE EARLY CLB WAS EXPECTED. WE CALLED BACK THE CLB AND ZNY DID NOT SAY OUR CALL WAS BLOCKED OR THAT IT WAS FOR ANOTHER ACFT.