If you want to pass 2 or more hashes to a subroutine, you really need to use references. Have a look at perldoc perlref, but basically the syntax is:

my %hashA = ( orange=>'good',
              apple=>'bad' );

my %hashB = ( here=>'today',
              gone=>'tomorrow' );

myfunction(\%hashA,\%hashB); # send references to the hashes

sub myfunction
{
  my $hashrefA = shift; # (or $_[0])
  my $hashrefB = shift; # (or $_[1])

  my %hashA = %$hashrefA; # treat the refs as hashes and
  my %hashB = %$hashrefB; # copy the contents

  $hashA{extravalue} = "change seen in the subroutine only";
  $hashrefA->{extravalue} = "change seen in the main program";

}
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Following on from sauoqs comments, with that syntax, %hashA and %hashB in the subroutine are still copies of the original hashes. If you want to manipulate the original hashes and have the changes seen by the main part of the program, you will have to manipulate the hashrefs. I've included an example of each in the snippet above. If all you want to do is e.g. print them out, the copies might be less unwieldy to work with, if you're not familiar with reference syntax.