POTENTIAL CONFLICT OCCURS WHEN A B757 FLT RESPONDS INCORRECTLY TO A WRONG CALL SIGN AND CLBS TOWARDS AN ALT OCCUPIED BY A CRJ; 50 MI NE OF EWR; NJ.

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RA WAS A DIRECT RESULT OF ACCEPTING A CLRNC FOR ANOTHER ACFT OF SIMILAR CALL SIGN; Y VERSUS X. CLRNC OF OTHER ACFT WAS REASONABLE TO US IN BOTH ALT AND CLRNC FIX. CONDITIONS OF DAY; VFR; AND HAVING CONFLICTING TFC Z IN SIGHT; DID NOT SCARE US; BUT MAY HAVE DELAYED MY QUERY WITH ATC TO CONFIRM LAST CLRNC. PASSING 16000 FT; OUR CLRED ALT AND CONVERGING WITH TFC Z I HAD FO CONFIRM ALT WITH ATC. WE WERE CLBING TO COMPANY FLT Y'S ALT OF 17000 FT. AT 16300 FT THE RA WAS ISSUED. AUTOPLT DISCONNECTED AND SHALLOW DSCNT MADE BACK TO 16000 FT. ATC CONFIRMED OUR ASSIGNED ALT AS 16000 FT. I ASKED ZNY IF THERE WAS AN ACR FLT Y ALSO ON THE FREQ; THEY SAID YES. THEN IT WAS OBVIOUS TO US WHAT HAD HAPPENED. I THOUGHT FOR A MOMENT I HEARD CTR SAY ACR Y INSTEAD OF ACR X; BUT IT MUST HAVE BEEN BROKEN OR GARBLED BECAUSE I DID NOT ASK THE COPLT TO CONFIRM CLRNC READBACK RIGHT AWAY. SUPPLEMENTAL INFO FROM ACN 597552: WE WERE ALSO CLRED TO 16000 FT. SHORTLY AFTER WE WERE GIVEN A 320 DEG HDG FOR TFC. TFC; AN ACR CRJ WAS SIGHTED BUT NOT RPTED DUE TO FREQ CONGESTION. CTR INFORMED US WE WERE NOT CLRED FOR 17000 FT AND TO RETURN TO 16000 FT AND 320 DEG HDG. WE LEARNED AFTER THE FACT THAT THE CALL HAD BEEN FOR COMPANY FLT Y BEHIND US; WHICH WE WERE UNAWARE OF UP TO THAT POINT.