2 ACR ACFT; SAME ACR; SAME LAST 3 DIGITS OF CALL SIGNS EXACTLY THE SAME. 1 CONFUSED DEP CTLR AND SOON 2 CONFUSED FLCS; MIXING AND SOMETIMES MATCHING TURNS; ALTS; AND CLRNCS CREATES A HAZARDOUS SIT IN DCA AIRSPACE.

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DURING DEP FROM DCA ON N DEP; THE ATC CTLR ON FREQ 125.65 APPEARED TO BE CONFUSED AND OVERTASKED; LEADING TO CONTRADICTORY HDG; RTE; AND ALT DIRECTIONS. WHEN WE SWITCHED TO 125.65 ON DEP; HIS FIRST COMMENT WAS 'OK XXXX; YOU'RE RIGHT IN THE MIDDLE OF IT; CLB AND MAINTAIN 9000 FT.' AT 7 DME ON THE 328 DEG RADIAL (DCA) ATC GAVE ACR XXX TURN R TO 140 DEGS. WE ANSWERED; ACR XXXX R TO 140 DEGS. AS WE PASSED THROUGH 360 DEGS IN A R TURN; ATC SAID; ACR XXXX TURN R 360 DEGS. THIS IS THE ONLY TIME HE USED THE CORRECT CALL SIGN. WE ACKNOWLEDGED; STOPPED THE TURN; AND HEADED 360 DEGS. ABOUT THIS TIME WE LEVELED AT 9000 FT. IMMEDIATELY AFTER OUR LEVELOFF HE GAVE ACR XXX TURN R 150 DEGS; CLB TO 15000 FT. DURING ACKNOWLEDGEMENT; THE CAPT ASKED HIM TO CONFIRM ACR XXXX TURN 150 DEGS; CLB TO 15000 FT. HE RESPONDED 'OK; XXXX CLB TO 15000 FT TURN TO 170 DEGS; VECTORS FOR PALEO.' PALEO WAS NOT ON OUR RTE. WHEN WE ASKED HIM ABOUT THE VECTOR AND BEFORE WE GOT TO 170 DEG HDG; HE TOLD US TO ROLL OUT HDG 090 DEGS. (THERE WERE SEVERAL OTHER ACFT ON THE FREQ ALL THIS TIME AND AT LEAST 1 TIME HE DIRECTED ACFT TO MAKE AN IMMEDIATE HARD TURN TO AVOID TFC.) ON THE 90 DEG HDG AND LEVEL AT 15000 FT; HE SAID; ACR XXX CLB TO 16000 FT. WE ACKNOWLEDGED AND STARTED THE CLB TO 16000 FT. AT 15300 FT ATC ASKED IF ACR XXX WAS MAINTAINING 15000 FT. WE ANSWERED; NO CLBING TO 16000 FT. ATC DIRECTED AN IMMEDIATE DSCNT TO 15000 FT AND AN IMMEDIATE L TURN TO 030 DEGS TO AVOID TFC. WE SAW THE TFC AT 12 O'CLOCK ON THE TCASII AT 16000 FT. WE STOPPED THE CLB BY 15500 FT AND RETURNED TO 15000 FT. THE TFC NEVER GOT CLOSER THAN 5 MI ON TCASII. SHORTLY AFTER THIS HE TURNED US OVER TO ZDC ON 134.5. THE REST OF THE CLB WAS NORMAL. AT NO TIME DURING OUR DEP AND CLB DID THE CTLR APPEAR TO KNOW 1) OUR CALL SIGN; 2) OUR RTE OF FLT; 3) WHAT INSTRUCTIONS HE HAD GIVEN US LAST. IF THE WX HAD NOT BEEN SO GOOD WE WOULD HAVE BEEN VERY WORRIED ABOUT OUR SAFETY.