Some elements from the following program might be useful for solving your problem. 

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11151901
use warnings;
use Path::Tiny;

local $_ = path('FILE1')->slurp . path('FILE2')->slurp;
my %seen;
while( /^(.*:)(.*)/gm )
  {
  $seen{$1}{$_}++ and print "$1$_\n" for split /~~/, $2;
  }

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In reply to Re: Find common substrings by tybalt89
in thread Find common substrings by Anonymous Monk

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