You could use
Click TextFX ? Click TextFX Tools ? Click Sort lines case insensitive (at column) Duplicates and blank lines have been removed and the data has been sorted alphabetically.
as indicated above. However, the way I did it because I need to replace the duplicates by blank lines and not just remove the lines, once sorted alphabetically:
REPLACE:
((^.*$)(\n))(?=\k<1>)
by
$3
This will convert:
Shorts
Shorts
Shorts
Shorts
Shorts
Shorts Two Pack
Shorts Two Pack
Signature Braces
Signature Braces
Signature Cotton Trousers
Signature Cotton Trousers
Signature Cotton Trousers
Signature Cotton Trousers
Signature Cotton Trousers
Signature Cotton Trousers
Signature Cotton Trousers
Signature Cotton Trousers
Signature Cotton Trousers
Signature Cotton Trousers
Signature Cotton Trousers
to:
Shorts
Shorts Two Pack
Signature Braces
Signature Cotton Trousers
That's how I did it because I specifically needed those lines.