A B737-200; ENRTE TO EWR; RESPONDED TO ANOTHER ACFT'S CLRNCS; DEVIATING FROM ASSIGNED ALT.

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ENRTE; WE EXTENSIVELY REVIEWED THE DYLIN 1 ARR FOR EWR SINCE IT WAS A NEW PROC FOR THE ARPT. WHILE LEVEL AT FL330; I MADE THE FAREWELL PA PRIOR TO TOP OF DSCNT. DURING THIS TIME; THE CAPT ACKNOWLEDGED A CLRNC TO CROSS OTT AT FL290. TIME OF THE EVENT WAS XA00. FREQ IN USE WAS XXX.87 ON COM #1 WHILE MONITORING YYY.5 ON COM #2. SHORTLY THEREAFTER; I ACKNOWLEDGED AN AMENDED CLRNC TO CROSS 10 MI N OF OTT AT FL290 AS THE CTLR STATED THAT WOULD AFFORD US MORE ROOM FOR THE DSCNT. LASTLY; THEY REQUESTED WE MAINTAIN 300 KIAS OR BETTER IN THE TRANSITION FOR SPACING. AS WE DSNDED THROUGH FL298 OVER OTT VOR; THE CTLR TOLD US TO 'CLB IMMEDIATELY TO FL310...YOU JUST ENTERED RESTR AIRSPACE OVER WASHINGTON.' MY INITIAL REACTION WAS THAT THE CLRNC WAS FOR THREAT TFC. REGARDLESS; WE DULY RETURNED TO FL310. SEPARATION WAS NOT COMPROMISED WITH ANY ACFT DURING THE ENTIRE EVENT. WORKLOAD FOR US WAS AVERAGE AND THE CTR FREQ WAS RELATIVELY BUSY. CLRNCS SEEMED TO BE DELIVERED WITH FEW; IF ANY; PROBS. SIMULTANEOUSLY; THE CTLR WAS GETTING INPUT FROM OTHER PLTS AS TO HOW TIGHT THE ARR'S XING RESTRS WERE WITH A STRONG TAILWIND AS WAS THIS CASE. EVIDENTLY; THE VERY SAME CTLR BUILT THE ARR HIMSELF; AS HE TOLD EVERYONE OVER THE RADIO. AFTER A FEW XMISSIONS TO OTHER ACFT; THE CTLR CAME BACK TO US AND SAID THAT WE ACCEPTED 3 CLRNCS INTENDED FOR ANOTHER ACFT. WE DID NOT RECALL ANY SIMILAR SOUNDING CALL SIGNS NOR DID ANYONE ADVISE THAT THE READBACKS WERE UNINTELLIGIBLE -- SIMILAR TO 2 RADIOS XMITTING CONCURRENTLY. NO FURTHER DISCUSSION OF THE INCIDENT TOOK PLACE BTWN ATC AND US AS WE CONTINUED TO EWR AND LANDED UNEVENTFULLY.