We are pleased to announce support for multiple TLS certificates on Network Load Balancers using Server Name Indication (SNI). You can now host multiple secure applications, each with its own TLS certificate, on a single load balancer listener. This allows SaaS applications and hosting services to run behind the same load balancer, improving your service security posture, and simplifying management and operations.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/09/elastic-load-balancing-network-load-balancers-now-supports-multiple-tls-certificates-using-server-name-indication/