>>The SYS(2007) function can create crc16 or crc32 depending on the parameter passed. At most it can return 2^16-1 and 2^32-1 different values respectively. It's quite possible that 2 files can have the same checsum returned by SYS(2007). I would recomend to use one of the Hash algorithm that return longer digest of the file. You can use Craig Boyd's Vfpencryption.fll to generate MD5 or stronger hash.
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>Wouldn't that be 2^16 and 2^32 ?

And it's significant how?