2 ACFT THAT WERE CONVERGING ON A VOR IN IMC; ASSIGNED THE SAME ALT. THE RPTING FLC OVERHEARD THE OTHER ACFT ASKING ATC IF ANOTHER ACFT WOULD BE LEVELING AT 9000 FT; AND RECOGNIZED THAT THE QUESTION WAS REGARDING THEIR ACFT. THEY ARRESTED THEIR CLB; AND LATER THROUGH FLT ATC REVIEW; LEARNED THAT BOTH ACFT HAD BEEN ASSIGNED THE SAME ALT.

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UPON DEP FROM POU; OUR INSTRUCTIONS FROM NY DEP CTL WERE TO PROCEED DIRECT TO PAWLING VOR; 55 DEG RADIAL TO STUBY; V487. CLB AND MAINTAIN 5000 FT. AT 5000 FT WE WERE HANDED OFF TO ZBW. WE WERE DIRECTED BY ZBW TO CLB TO AND MAINTAIN 10000 FT. IN THE VICINITY OF PAWLING VOR; WE WERE CLBING THROUGH 9000 FT AT 1500 FPM CLB RATE WHEN ANOTHER ACFT QUESTIONED ZBW IF THE 'ACFT WAS LEVELING OFF AT 9000 FT?' I AM UNCERTAIN OF CTR'S RESPONSE; BUT THE CONVERSATION LED ME TO BELIEVE WE WERE POSSIBLY IN CONFLICT. I INSTRUCTED THE FO TO REDUCE THE CLB RATE AS THE OTHER ACFT RPTED A RA FROM HIS TCASII. AT THAT TIME WE WERE AT 9600 FT LEVELING AND THEN DSNDING TOWARDS 9000 FT SINCE ALL INDICATIONS WERE THAT WE WERE IN CONFLICT WITH THE OTHER ACFT. BOSTON THEN RESPONDED TO THE QUESTIONING ACFT THAT THEY WERE PASSING BEHIND THE ACFT IN QUESTION. WE WERE THEN CLRED TO A HIGHER ALT (13000 FT; I THINK) AND THE OTHER ACFT WAS GIVEN A PHONE NUMBER TO CONTACT AFTER LNDG. ABOUT 3 MINS LATER I TOO WAS GIVEN THE SAME PHONE NUMBER AND INSTRUCTIONS TO CALL. AT MY DEST I PLACED MY PHONE CALL. MY CONVERSATION WAS WITH ZBW. WE DISCUSSED THE SIT AND THE CTLR STATED THEY HAD REVIEWED THE TAPES. HE SAID HE WAS A BIT UNCERTAIN ABOUT MY COMMENTS ABOUT 9000 FT. I EXPLAINED THE SEQUENCE OF EVENTS RELATED ABOVE. HE THEN STATED THAT THE CTLR HAD ASSIGNED US BOTH THE SAME ALT. SINCE WE WERE IN IMC CONDITIONS; I COULD NOT DETERMINE THE PROX OF THE CONFLICT. OUR TCASII WAS INOP AND WRITTEN UP ON A PREVIOUS MISSION AS PER OUR MEL. HAD MY TCASII BEEN OPERATING; PERHAPS I COULD HAVE PLAYED A MORE ACTIVE ROLE IN AVOIDING THIS CONFLICT. SUPPLEMENTAL INFO FROM ACN 327420: 2 ACFT WERE ASSIGNED THE SAME ALT; 10000 FT. CONTRIBUTING FACTORS: TCASII OF ACFT WAS MEL'ED AND 2 ACFT CLRED THROUGH ONE VOR AT SAME RATE OF CLOSURE. WHEN THE CAPT SWITCHED OFF COM #1 AND ADVISED PF; THE PF COVERED THE COM. ZBW CLRED US TO 10000 FT. THE PF READ BACK; 'MAINTAIN 10000 FT.' THE PF RESET ALT ALERTER AND ADVISED PNF OF NEW ALT BY SAYING 'CLRED TO 10000 FT' AND POINTING TO THE ALT ALERTER. THE CAPT ACKNOWLEDGED 'CLRED TO 10000 FT' AND POINTING TO ALT ALERTER AS HE SWITCHED BACK TO COM #1. ZBW THEN ADVISED TFC 11 O'CLOCK SEBOUND 10000 FT. PNF ADVISED ROGER IMC. AT THAT TIME WE SHOULD HAVE REQUESTED OR QUERIED OUR ASSIGNED CLB PROFILE ALT.