ACR B767 FLC ACKNOWLEDGED A CLRNC FOR ANOTHER ACR AND CAME INTO CONFLICT WITH A BE90 ABOVE THE B767. THE B767 THOUGHT A DSCNT CLRNC TO THE ACR ACFT WAS A CLB CLRNC FOR ITSELF.

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ACFT #1; B767; AN OVERSEAS DEP OFF OF IAD; CLBED TO 17000 FT; INFORMED OF TFC AT FL180 (A KING AIR; ACFT #2; SBOUND AT FL180). TFC EXCHANGED. KING AIR SEES B767. KING AIR IS TURNED AWAY FROM TFC SO TO ALLOW B767 TO CLB SOONER. ACFT #3 WAS ON A STAR TO PHL; WAS ISSUED A DSCNT CLRNC THAT ACFT #1 MISTOOK FOR A CLB CLRNC. CTLR DID NOT CATCH THE ACFT #1 CLB READBACK AND ISSUED OTHER CLRNCS. ACFT #3 CAME BACK AND INFORMED CTLR THAT SOMEONE ELSE TOOK HIS CLRNC AND WAS IT FOR HIM. A DSCNT CLRNC WAS REISSUED TO ACFT #3 IN WHICH ACFT #1 RESPONDED ROGER; CLBING TO FL200. ACFT #1 TOLD NEGATIVE; MAINTAIN 17000 FT FOR TFC. ASKED TO VERIFY HIS ALT; ACFT #1 SAID 17800 FT DSNDING. KING AIR ACFT #2 ASKED IF HE HAD TFC IN SIGHT. THE KING AIR RESPONDED YES AND THAT TFC WAS NO FACTOR. SIT AROSE FROM A PLT WHO WAS IN A HURRY TO CLB AND POSSIBLY FROM A CTLR ISSUING A CLRNC THAT COULD NOT BE MISUNDERSTOOD AND DIDN'T LISTEN TO READBACK AS CLOSELY AS POSSIBLE. SUPPLEMENTAL INFO FROM ACN 413811: THE B767 TOOK ANOTHER ACFT'S CLRNC AND CLBED INTO THE KING AIR CAUSING A LOSS OF SEPARATION. SUPPLEMENTAL INFO FROM ACN 414254: ON CLBOUT FROM IAD AT 17000 FT; ZDC HAD GIVEN A CLB CLRNC. CAPT READ BACK THAT CLBING TO FL200 AND THEN SET ALT WINDOW. FO BEGAN CLB. ANOTHER ACFT ON FREQ TO ZDC STATED THAT ANOTHER ACFT HAS MISTAKEN THE CLB CLRNC. AT THAT TIME CAPT ASKED ZDC ABOUT ALT CLRNC. ZDC RETURNED US 17000 FT. ON DSCNT TO 17000 FT; CAPT AND FO HAD RECEIVED A TA ON TCASII. ACFT WAS APPROX 1 MI HORIZ SEPARATION. ACFT HAD US IN SIGHT. THERE WERE NO FURTHER COMMENTS FROM ZDC. IN RETROSPECT; I REALIZE THAT AT THE TIME OF THE CONFUSION; I WAS NOT FULLY LISTENING TO CTR COMS. I WAS BEGINNING MY FO RELIEF DUTIES AND HEARD THE CAPT READ BACK THE CLB CLRNC; BUT DID NOT FULLY HEAR THE CLB CLRNC BEING GIVEN. I SHOULD HAVE QUESTIONED IT IMMEDIATELY.