ACR Z HAD LTSS FROM SMA XXX WHEN CLTR USED WRONG CALL LETTER. SYS ERROR.

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AFTER I TOLD SMA XXX TO HOLD SHORT OF RWY 22R; TFC IN THE FLARE HE ACKNOWLEDGED. THERE WAS AN ACR Z OVER THE NUMBERS IN THE FLARE. HOLDING SHORT OF RWY 22L WAS LTT XXY. THERE WAS A WIND SHIFT SO WE WERE LNDG AND DEPARTING RWYS 22L; 22R; 31C. I THEN THOUGHT I SAID LTT XXY CROSS RWY 22L TURN R ON YANKEE; L ON KILO AND HOLD SHORT OF THE TIE DOWN FOR YOUR DELAY. IN ACTUALITY I SAID LTT XXX CROSS RWY 22L TURN R; ETC. WHEN I FINISHED I SAW SMA XXX START TO MOVE. AT THIS TIME THERE WAS 3 SECONDS OF STATIC AND SQUEAL FROM 3 ACFT CALLING GND. I STATED QUITE LOUDLY XXX STOP; AT THIS TIME HE WAS STILL SHORT OF RWY 22R. SMA XXX CONTINUED ACROSS RWY 22R WITH ACR Z ROLLING SLOWLY OUT APPROX 1000 FT UP RWY (NEVER EVEN GOT CLOSE). WHEN WE TALKED LATER ON THE TELEPHONE TO THE PLT OF XXX HE SAID HE HEARD XX SOMETHING SO HE WENT AHEAD; ADDITIONALLY WHEN ASKED OF ACR Z HE SAID HE SAW IT AND THOUGHT HE BETTER HURRY ACROSS. AS A CTLR I SHOULD HAVE STRESSED THE FACT OF SIMILAR SOUNDING CALL SIGNS. AS THE PLT I BELIEVE HE SHOULD BECOME MORE AWARE OF THE ARPT AND LISTEN MORE CAREFULLY.