Requesting SSL certificates with more than one domain

When requesting an ACM certificate, AWS will ask you to add some CNAME records in Route 53 (or your DNS provider if not using Route 53) to prove you own the domain.

If you are requesting a certificate that covers multiple domains (e.g. "yourwebsite.com" and "*.yourwebsite.com", or any other certificate with more than one entry), ACM may show you duplicate CNAME records to enter into your DNS provider. This normally causes an error when you try to add them, unless you look closely at the records you're being asked to add.