use strict; use warnings; use 5.010; my $text = 'S55 1.1.1.1 S66 2.2.2.2 S55 1.1.1.1'; $text =~ s/\b(\w+\d+\s*\d+\.\d+\.\d+\.\d+)\s*\1\b/$1/ig; say $text; --output:-- S55 1.1.1.1 S66 2.2.2.2 S55 1.1.1.1