A DH8 UNEXPECTEDLY MADE A 180 DEG TURN ON THE RWY AT CLT TO EXIT WITH TFC FLARING ON THE APCH END.

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I WAS WORKING THE LCL E POS AND IN THE MIDDLE OF AN ARR PUSH AND A DEP PUSH. ACFT LNDG RWY 23 AND DEPARTING RWY 18L. THERE WAS AN 8 KT TAILWIND ON FINAL AND MOST ACFT WERE FAST OR HIGH. LNDG ACFT HAD TO BE TOLD TO EXPEDITE OFF THE RWY FOR THE NEXT ARR. NUMEROUS RWY XINGS ON BOTH RWYS AND HELI TFC ALSO INCREASED WORKLOAD. ACR X WAS CLRED TO LAND ON RWY 23; ACR Y ON A VISUAL APCH BEHIND ACR X AND DID NOT HAVE ACR X IN SIGHT. ACR Y WAS OVERTAKING ACR X AND I REDUCED HIM TO FINAL APCH SPD. ACR X WAS OBSERVED XING THE THRESHOLD AND I COORDINATED WITH GND CTL A RWY XING ON RWY 18L. WHEN I LOOKED AT ACR X NEXT HE APPEARED TO BE PASSING TXWY B (A NORMAL TURNOFF POINT FOR THIS ACFT). I TOLD HIM TO EXPEDITE TO TXWY F OR IF HE COULD MAKE TXWY M2 (A FORWARD HIGHSPD NEXT TO TXWY B) TURN R. ACR X SAID 'IF I CAN MAKE A QUICK U-TURN.' BEFORE I COULD ANSWER HIM; HE MADE A 90 DEG R TURN AND APPEARED TO BE EXITING AT TXWY M2. I RECLRED ACR Y TO LAND. AS ACR Y WAS FLARING OUT; ACR X CONTINUED OPPOSITE DIRECTION ON RWY 23 PAST TXWY M2 AND EXITED THE RWY L AT TXWY B. I BELIEVE THAT WHEN THE TAIL WIND ON THE FINAL WAS FIRST NOTICED AND BROUGHT TO OTHER'S ATTN 45 MINS EARLIER; THAT OUR OP SHOULD HAVE SWITCHED TO PARALLELS N. I BELIEVE FINAL CTLRS SHOULD HAVE PROVIDED ADDITIONAL SPACING ON THE FINAL DUE TO THE TAILWIND. I BELIEVE I SHOULD HAVE SENT ACR Y AROUND AND NOT ASSUMED ACR X WOULD EXIT AT TXWY M2.