Remove duplicate records in RRset before verifying
Remove duplicate records in RRset before verifying

As suggested in RFC4034 section 6.3

smogali/getdns,smogali/getdns,smogali/getdns,shane-kerr/getdns,huitema/getdns,huitema/getdns,smogali/getdns,shane-kerr/getdns,shane-kerr/getdns,shane-kerr/getdns,huitema/getdns,huitema/getdns