Without repeating the extension: 
use strict;
use warnings;

use File::Find::Rule qw( );

my %files;
for (
   File::Find::Rule
      ->file()
      ->name('*.rtf', '*.ftp')
      ->in('.')
) {
   my ($name) = /^(.*)\./;
   ++$files_by_ext{$name};
}

say for grep {$files{$_} == 2} keys %files;

[download]

In reply to Re^4: Printing files that has two different extensions in a given directory by JavaFan
in thread Printing all the files that have both ".rtf" and ".ftp" by searching recursively in a given directory by Anonymous Monk

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