LESS THAN STANDARD SEPARATION BETWEEN 2 ACR. OPERATIONAL ERROR.

Narrative

ACR X (M82) AT FL310 SWBND OVERTAKING ACR Z (M78) AT FL310 OVER NORFOLK AND ACR X WAS XING WITH A CORP JET AT FL310 W OF NORFOLK 8 MI SBND TO DIXON VORTAC. THE SALISBURY HIGH CTLR DSNDED ACR X TO FL280 AFTER COORDINATING WITH US AND AFTER HE REALIZED HE WAS GIVING US A PAIR OF FL310'S. WE COULD NOT SEE THE ALT ON NBOUND ACR Y BECAUSE THE DATA TAG WAS OVERLAPPED WITH A PASSING ACFT. TFC CONDITIONS WERE MODERATE-HEAVY WITH OJT ON RADAR IN PROGRESS. 2 OTHER ACFT WERE ON VECTORS FOR WX AND TFC AT THE TIME. WHEN WE MOVED THE DATA TAG ON ACR Y AND THE TAG OF ACR X WHO WAS NOW ALSO OVERLAPPING PASSING TFC; I SAW THE CONFLICTION AND GAVE IMMEDIATE TURNS TO BOTH AND CALLED TFC TO BOTH PLTS WHO RPTED SEEING EACH OTHER. ACFT PASSED APPROX 1 MI AND APPROX 500'. OTHER: SIMILAR CALL SIGNS; OJT ON RADAR IN PROGRESS; WX DEVIATIONS; CORP JET AT FL310 REAL SLOW WITH NUMEROUS OTHER ACFT AT FL310 DURING MODERATE-HEAVY TFC CONDITIONS. ANOTHER CORP AT FL260 SWBND ACROSS WASHINGTON AND BALTIMORE DEP PATH CLBING TO FL260. ACR X AT M82 OVERTAKING ACR Z AT M78 BOTH AT FL310. ACR Y NBOUND AT FL290 DATA TAG OVERLAPPED WITH ANOTHER PASSING ACFT. SUPPLEMENTAL INFO FROM ACN 93112: WE WERE CRUISING AT FL310 AND WERE ADVISED THAT WE WERE OVERTAKING SLOWER TFC. WE WERE GIVEN DSCNT CLRNC TO FL280. ATC CHANGED US TO ANOTHER FREQ AND WE WERE GIVEN AN IMMEDIATE LEFT TURN. I STOPPED THE DSCNT AT 29600' WHILE INITIATING A 30 DEG BANK LEFT TURN. THE ON-COMING TFC WAS AT FL290 ON THE SAME FREQ. HE INITIATED A LEFT TURN ALSO. WE BOTH THEN HAD EACH OTHER VISUALLY; 600' VERT; 1/2 MI HORIZ. BETTER ATC COORD WAS NEEDED IN THIS CASE.