Which could also be done as the following one liner:

perl -e' while(<>) {print unless $s{(split /\|/)[0]}++;}' < infile > o
+utfile
[download]

where infile is a file with the values to parse and outfile is where you want the results.

Indeed:

perl -i.bak -e' while(<>) {print unless $s{(split /\|/)[0]}++;}' infil
+e
[download]

will edit infile in situ (putting backup in infile.bak).

Update: I have assumed that you are using a shell with redirection, such as bash. I have been told off for this sort of assumption before so best to make it clear.

--tidiness is the memory loss of environmental mnemonics