let
cat duplicate.txt
QWASEDRF1234567890098765
abc@quebex.com 000000000-932333 678394-56=3 9033894
QWASEDRF1234567890098765
abc@quebex.com 000000000-932333 678394-56=3 9033894
OPIUYTREE0986666544443322
dcsx@olivaa.net 123456678-rererrrde 09655584-35=6 77778
OPIUYTREE0986666544443322
dcsx@olivaa.net 123456678-rererrrde 09655584-35=6 77778
KILOPJUY23415000000003537 roaringrat@hscd_com 2008-02-020014243.99 0000758 00284.00 2008-03-01SEMENZA, CATHY E 000000000000016.03 000000000000000.00 CBB00010000000920
KILOPJUY23415000000003537 roaringrat@hscd_com 2008-02-020014243.99 0000758 00284.00 2008-03-01SEMENZA, CATHY E 000000000000016.03 000000000000000.00 CBB00010000000920
AQWSEDFR298099000003537 poiuty@hpoiyuj-usa_com 2008-02-020000823.15 0011676 00017.00 2008-03-01HJORTH,ROGER C 000000000000051.66 000000000000040.00 CBB00010000000906
AQWSEDFR298099000003537 poiuty@hpoiyuj-usa_com 2008-02-020000823.15 0011676 00017.00 2008-03-01HJORTH,ROGER C 000000000000051.66 000000000000040.00 CBB00010000000906
then
$ awk '{ a[$1]=$0 }
> END{
> n = asort(a)
> for (i=1;i<=n;i++) print a[i]
> }' duplicate.txt
AQWSEDFR298099000003537 poiuty@hpoiyuj-usa_com 2008-02-020000823.15 0011676 00017.00 2008-03-01HJORTH,ROGER C 000000000000051.66 000000000000040.00 CBB00010000000906
KILOPJUY23415000000003537 roaringrat@hscd_com 2008-02-020014243.99 0000758 00284.00 2008-03-01SEMENZA, CATHY E 000000000000016.03 000000000000000.00 CBB00010000000920
OPIUYTREE0986666544443322
dcsx@olivaa.net 123456678-rererrrde 09655584-35=6 77778
QWASEDRF1234567890098765
abc@quebex.com 000000000-932333 678394-56=3 9033894