Mcdarren,
I like your 1st version, but it seems to me it'll only work for even nums of duplicates eg if an item occurs 3 (5,7,9...) times, it'll be re-instated/preserved by your script?
Of course, the OP's example file only has duplicates in 2s, but the description doesn't state whether this is always the case.
I agree about using a hash, but I'd keep a count of all lines and test for cnt == 1 after looping through the input

Cheers
Chris

In reply to Re^2: Read file line by line and check equal lines by chrism01
in thread Read file line by line and check equal lines by Anonymous Monk

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