while (<DATA>) {
   my ($key, $value) = /(\S+) (.*)/ or next;    # or:
   my ($key, $value) = split;                   # or:
   (undef, $key, $value) = split(/\s+/, $_, 3);

   $hash{$key} = $value;                        # or:
   push(@{$hash{$key}}, $value);
}