Marginally less overhead if the data is sorted: 
 perl -lane 'print unless $F[0] eq $prev;$prev=$F[0]' < file2.txt > fi
+le1.txt

[download]
Also, the OP's code handles the boundary condition for the first record, but not the last.

     "As you get older three things happen. The first is your memory goes, and I can't remember the other two... " - Sir Norman Wisdom

In reply to Re^2: Remove Duplicates!! Please Help by NetWallah
in thread Remove Duplicates!! Please Help by nashkab

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