Checking duplicate values

I created two cursors
But it takes too long because VFP has to scan all records in both cursors

It there a better method the this below ?

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SELECT AP
SCAN
SELECT AP2
aax = 0
SCAN FOR AP2.ID2 = AP.ID2
aax = aax + 1
IF aax > 1
= MESSAGEBOX("Duplicated record")
endif
ENDSCAN
ENDSCAN
= MESSAGEBOX ("endSCAN")
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