use strict;
my $str = '<sku>V31L-CPFIJK-11077</sku>
<image1>https://testtest.pl/getled/sku-11077sku-11077.jpg</image1>
<image2>https://testtest.pl/getled/sku-11077sku-11077,1.jpg</image2>
<sku>V31L-CPFIJK-11033</sku>
<image1>https://testtest.pl/getled/sku-11033sku-11033.jpg</image1>
<image2>https://testtest.pl/getled/sku-11033sku-11033,1.jpg</image2>';
my $regex = qr/sku-(\d+)sku-\1/mp;
my $subst = '$1';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html