ARTCC CTLR CLRED AN ACR B727 TO DSND AND CROSS LAMMA INTXN AT 15000 FT ON STAR INTO MCO. THE B727 WAS FOLLOWING A B767 ON THE STAR THAT HAD A CARGO DOOR PROB AND WAS RESTR TO 270 KTS. THE B727 MISINTERP ALT XING RESTR AND DSNDED BELOW 15000 FT. CTLR RPTR SAW MODE C READOUT AND ALT INFRACTION AT 13400 FT AND TRIED TO STOP THE B727 AT 13000 FT. ACFT OVERSHOT THAT ALT AND LTSS OCCURRED.

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THE B767 WAS LEVEL AT 12000 FT OVER OMN BITH07 MCO. THE B727 WAS DSNDING TO 15000 FT; ABOUT 4 OR 5 MI IN-TRAIL; ROUTED OMN BITH07 COF; AND HAD A RESTR TO CROSS LAMMA AT AND MAINTAIN 15000 FT. PLT READBACK SOUNDED LIKE ROGER LAMMA AT 15000 FT. THE B767 WAS RESTR TO 270 KTS DUE TO A CARGO DOOR PROB. THE B727 WAS NOT SPD RESTR. THE B727 WAS OBSERVED DSNDING BELOW 15000 FT (MODE C) AND WAS IMMEDIATELY INSTRUCTED TO MAINTAIN 13000 FT. PLT REPLIED; ROGER 13000 FT WE'RE GOING TO HAVE TO GO BACK UP; MODE C INDICATED 13400 FT. TFC CALL WAS ISSUED (B767); PLT OF B727 RPTED TFC IN SIGHT. I INSTRUCTED B727 TO MAINTAIN VISUAL SEPARATION FROM B767 AND CLB AND MAINTAIN 15000 FT. PLT ACKNOWLEDGED. I QUESTIONED PLT FOR ASSIGNED ALT. PLT (B727) SAID HE 'READ BACK (11000 FT) ONE ONE THOUSAND;' AND TO 'CHK THE TAPE.' SUPVR IN-CHARGE WAS NOTIFIED OF VERBIAGE ON RADIO AND WAS AT THE SECTOR DURING THE EVENT. SUPVR WAS TRYING TO SHOW DEVELOPMENTAL A SPD FUNCTION OF THE COMPUTER WHEN INCIDENT STARTED. SUPVR TOLD THE WATCH DESK 'VISUAL SEPARATION.'