use strict;
my $str = 'Chiaro Gallo (blabla) (blabla)
Ricard Michaeln ()
Marco Liu (Hong Kong Stock Co Ltd) Hong Kong Stock Co Ltd
Rafiq (Kkska Traning Co (p) Ltd) Kkska Traning Co (p) Ltd
';
my $regex = qr/\((.*)\).*?\(?\1\)?/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