SMA OVERTOOK ANOTHER SMA ON FINAL AND WAS ON WRONG FREQ. TWR INTERVENED AND TURNED TO FIRST SMA FOR SEPARATION.

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SMA X ON FINAL TALKING TO LCL AND SMA Y SEQUENCED TO FOLLOW THE SMA X. SMA Y SAW AND ACKNOWLEDGED WHO HE WAS TO FOLLOW. HE CHANGED FREQ; BUT TO MCCONNELL GND INSTEAD. HE OVERRAN THE SMA X BUT DIDN'T LAND AS HE HAD NO LNDG CLRNC. SMA X SAW THE SMA Y PASS ABOVE AND TO HER LEFT. THE TRNEE WHOM I WAS WATCHING AND I TRIED TO CALL SMA Y WHEN HE APPEARED TO OVERTAKE SMA X; BUT TO NO AVAIL. HE ISSUED INSTRUCTIONS TO SMA X TO MAKE A RIGHT 270 AWAY FROM FINAL. TFC WAS MODERATE TO HEAVY ON A 1 RWY OPERATION. THIS COULD POSSIBLY HAVE BEEN PREVENTED IF SMA Y HAD THE APPROPRIATE FREQS. IT APPEARED THAT THE PLT WAS LOW TIME AND SOMEWHAT DISORIENTED WHEN HE CALLED INITIALLY ON RADAR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING. SMA Y TOLD APCH CTL THAT HE HAD THE SMA X IN SIGHT AND WAS ADVISED TO FOLLOW THAT ACFT. TAPES SHOWED THAT APCH CTL GAVE SMA Y A FREQ CHANGE AND HAD INDICATED THE PROPER TWR FREQ. NOT KNOWN WHY THE SMA Y CHANGED TO THE WRONG FREQ. TWR CTLRS WERE USING BOTH BRITE RADAR AND VISUAL SCAN OUT THE WINDOW TO JUDGE ACFT POS. WHEN OVERTAKE WAS OBSERVED; BOTH THE TRNEE AND THE RPTR TRIED TO CONTACT THE SMA Y; BUT WERE UNABLE. SMA X WAS GIVEN TURN AND RESEQUENCED BEHIND THE OTHER ACFT. APPARENTLY; SMA Y WAS LOW TIME PLT AND GOT CONFUSED. INCIDENT WAS CLASSIFIED AS A PLT DEVIATION.