If I enable a deployment that is only assigned to a single server group, I get this:

[Server:server-one] 17:49:28,770 INFO [org.jboss.as.server.deployment] (MSC service thread 1-2) Starting deployment of "test-application.war"
[Server:server-two] 17:49:28,771 INFO [org.jboss.as.server.deployment] (MSC service thread 1-2) Starting deployment of "test-application.war"
[Server:server-one] 17:49:29,315 INFO [org.jboss.web] (MSC service thread 1-1) registering web context: /test-application
[Server:server-two] 17:49:29,412 INFO [org.jboss.web] (MSC service thread 1-1) registering web context: /test-application

Likewise, disabling it for a specific group doesn't have no effect.