Terraform Enterprise High Availability deyploment


I am about to implement the recommended architecture on https://www.terraform.io/docs/enterprise/before-installing/reference-architecture/aws.html#infrastructure-diagram..

However, how can I make that if the ASG scales out to 2 instances due to a high load both instances stay in sync?
Currently I do not understand how this is meant to be. If somewhen changes the TFE config on server then, it must also be changed on the other one.