My first suggestions would be to look in perlman:perlfaq5 or even perlref.

open (FILEHANDLEONE, "myfile1.txt") or die "couldn't open file\n";
open (FILEHANDLETWO, "myfile2.txt") or die "couldn't open file\n";

&SubName(\*FILEHANDLEONE,\*FILEHANDLETWO) or die "Couldn't do somethin
+g : $!\n";

sub SubName{
  my ($fhone, $fhtwo) = @_;
  
  while (<$fhone>){
    #process file one
  }

  while (<$fhtwo>){
    #process file two
  }
  
  return 1;

}
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C-.