use strict;
use warnings;

my %seen; # here we note addresses we saw already
while (<DATA>){
    my ($country, $city, $street, $number, $name) = split;
    next unless ++$seen{$country}{$city}{$street}{$number} == 2;
    print "Second name at $city, $country, $street, $number is $name\n";
}
__DATA__
Country City1 Street1 number1 name1
Country City1 Street1 number1 name2
Country City1 Street1 number2 name3
Country City1 Street2 number1 name4
Country City1 Street2 number1 name5