this and that
fish and chips and mushy peas
the cat and catkin
boom bang boom

##</code><code>##

#!/usr/bin/perl
#
use strict;
use warnings;

my $inputFile = q{spw888564.txt};
open my $inputFH, q{<}, $inputFile
   or die qq{open: < $inputFile: $!\n};

while ( <$inputFH> )
{
    next unless m{(\w+).*\b\1\b};
    print qq{Found '$1' repeated in: $_};
}

close $inputFH
   or die qq{close: < $inputFile: $!\n};

##</code><code>##

Found 'and' repeated in: fish and chips and mushy peas
Found 'boom' repeated in: boom bang boom