my $second

##</code><code>##

  my $line = $_

##</code><code>##

while(<>) {
  my $line = $_;
  my($first, $second) = split(/\|/, $line);   # or: "\\|"
  my @list = ($hash{$first}, $second);
  $joined = "@list";  # joins with space by default (see $" )
  $hash{$first} = $joined;
}