#!/usr/bin/perl

use warnings;
use strict;

my (%foos, %bars);
while( my $line = <DATA> ) {
  chomp $line;
  if ( my ( $key, $val ) = $line =~ /^foo ([^:]*):([^:]*)$/ ) {
    push( @{ $foos{ $key } }, $val );
  } elsif ( my ( $key, $val ) = $line =~ /^bar ([^:]*):([^:]*)$/ ) {
    push( @{ $bars{ $key } }, $val );
  } else {
#    warn qq( "$line" is the wrong format.\n );
  }
}

__DATA__
foo key1:val1
bar key2:val2
foo key3:val3
bar key4:val4
3 bad:val