If you deploy the same war twice (same hash with different names) on a domain then undeploy one the content is removed from the HC while it is still referenced and potentially useable.
The content is not removed from the servers content directory.
To reproduce :
deploy /home/ehsavoie/dev/wildfly/quickstart/ejb-in-war/target/wildfly-ejb-in-war.war --runtime-name=first.war --server-groups=main-server-group --name=first.war
deploy /home/ehsavoie/dev/wildfly/quickstart/ejb-in-war/target/wildfly-ejb-in-war.war --runtime-name=second.war --server-groups=main-server-group --name=second.war
undeploy first.war --all-relevant-server-groups