ELB Classic & ELB Application Load Balancer don't support multiple SSL certificates. There is support multiple Subject Alternative Names (SANs https://en.wikipedia.org/wiki/Subject_Alternative_Name)

And there is support for wildcard certificates, *.example.com

You can request a cert through AWS Certificate Manager with multiple names, more info https://docs.aws.amazon.com/acm/latest/userguide/gs-acm-requ...

This is not using Server Name Indicator / SNI.