my %seen;
while (<DATA>) {
    /^([^\|]+)\|(.*)/; # split at the first "|"
    my ($key, $value) = ($2,$1);
    next if $seen{$key};
    print "$key: $value\n";
    $seen{$key}++;
}
__DATA__
34|4|45|56|45
45|34|45|00|23
45|34|45|00|27
34|4|456|56|03
36|4|456|56|03