#!/usr/bin/perl

use strict;
use warnings;

#SSCCE:
my %mycorpus = (

            text1 => "This is line 1 from text 1
another line here which should be included in the text file with the above line.
This is line 2 from text 1
This is line 3 from text 1",
            
            
            text2 => "This is line 1 from text 2
This is line 2 from text 2
another line here which should be included in the text file with the above line.
This is line 3 from text 2",

);

my $count = 1;

foreach my $filename (sort keys %mycorpus)
  {
  for ( $mycorpus{$filename} =~ /This is(?:(?!This is).)*/sg )
    {
    my $outputname = 'UserA_' . $count++ . '.txt';
    open my $outfile, '>', $outputname or die "$! opening $outputname";
    print $outfile "$_\n"; # \n only if desired
    close $outfile;
    }
  }

# for testing file contents
system "more UserA* | cat";