NMAC OR NEAR FORMATION FLT.

Narrative

I HAD CALLED FRG TWR AND HAD BEEN ASSIGNED A 'STRAIGHT IN' APCH TO RWY 32. I WAS INSTRUCTED TO CALL THE TWR WHEN 8 MI FROM THE RWY. APPROX 2-3 MIN AFTER MY CALL; I HEARD A SECOND PIPER CHEROKEE CALL FRG; RPT A POS CLOSE TO MINE AND BE GIVEN A 'STRAIGHT IN' APCH TO RWY 32; AGAIN REQUESTING HE CALL WHEN 8 MI FROM RWY. I BEGAN AN INTENSIVE SCAN OF THE AREA. NO ACFT SIGHTED. THE TWR BECAME CONCERNED AND ASKED THE SECOND ACFT TO BE MORE PRECISE ABOUT ITS LOCATION. HE RPTED A POS QUITE CLOSE TO MINE. THE TWR ASKED ME IF I HAD THE SECOND ACFT IN SIGHT; AND JUST AS THEY DID SO; I ACQUIRED THE ACFT VISUALLY; ABOVE AND TO MY L. IT WAS CLOSE ENOUGH FOR ME TO READ ITS NUMBERS. THE TWR REQUESTED I MAKE A 360 TO MY L. I ASKED FOR A R 360 DEG TO AVOID TURNING 'INTO' CONFLICTING TFC. MY R TURN WAS APPROVED; AND I FELL INTO LINE BEHIND THE ACFT. I LANDED WITHOUT INCIDENT. OF NOTE; WAS THE FOLLOWING SEQUENCE: THE TWR; TOLD ME THAT MY RETURN WAS 'WEAK;' THEY DID NOT SPECIFY WHETHER OR NOT MY XPONDER WAS WORKING. I OFFERED TO 'RECYCLE' THE XPONDER AND DID SO; PLACING IT INTO STANDBY; THEN AGAIN INTO ALT MODE. THE TWR AGAIN SAID THE RETURN WAS WEAK. HOWEVER APPROX 30 SECONDS AFTER MY RECYCLE; THE TWR RPTED RECEIVING A STRONGER SIGNAL. MY XPONDER LIGHT WAS INDICATING THAT MY ACFT WAS BEING INTERROGATED; SO I BELIEVE IT WAS OPERATING PROPERLY. THE TWR USES A 'SLAVED' RADAR RETURN FROM ISP. COULD THE 2 TARGETS HAVE BEEN CLOSE ENOUGH TO CONFUSE THE RADAR? FRG IS AN EXTREMELY BUSY ARPT (3RD BUSIEST IN NYS).