HI, I have a tab separated file which may run upto 5000 lines. The file format is some thing like this: 
XXXXXS331632    XXXXXS331632    female  40087   a5
XXXXXS331632    XXXXXS331632    female  47735   a5
XXXXXS331681    XXXXXS331681    male    40087   e6
XXXXXS331681    XXXXXS331681    male    47735   e6
XXXXXS331856    XXXXXS331856    male    40177   d1
XXXXXS331856    XXXXXS331856    male    47737   d1

[download]
What I really want to do is delete the row that appears twice irrespective of the difference(40087 , 47735) in the 4th column. I could remove either the first or the the second entry. At the end what I like to have is a file with the duplicate(?) entry removed.
Something like this:
XXXXXS331632    XXXXXS331632    female  40087   a5
XXXXXS331681    XXXXXS331681    male    40087   e6
XXXXXS331856    XXXXXS331856    male    40177   d1

[download]
Any suggestions please
Thanks for your time.

In reply to Remove duplicate lines in a file by Anonymous Monk

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