the author of CGI.pm knew that people want to do exactly what you're trying to do, so there's no need to do it yourself.

use CGI ();
my $q = new CGI;
open FILE, ">>testing123.text" or die $!; # error checking is importan
+t! always!
$q->save(FILE);
close FILE;
[download]

and you're done! no need to do that parsing and stuff yourself.
if you really only want two specific form fields and your own format, then please use the CGI::param method, as it is working correctly and will decode the values for you.
if you don't want to decode the values, then, please provide more info like input data and output (rectangle is not really a rectangle but it means an unprintable character. use an editor to find out which character it is.)