Buried treasure! A zip file contains two copies of the file metadata, one just before the data and one at the end of the zip. Unzip uses the first one, and ziptest.pl uses the second. Neither one notices that the two copies don't match. You can modify my little script like this to make ziptest.pl complain: 
while ($data =~ /PK\x01\x02/g) ... # find all file headers
substr($data, $offset[1]+16, 1) ^= "\x01"; # change the crc

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In reply to Re^5: File integrity checker by Anonymous Monk
in thread File integrity checker by roperl

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