JBAS014803: Duplicate resource ... when trying to use deployment-overlay link in JBoss EAP 6.x

Issue

• We are getting JBAS014803: Duplicate resource when running the deployment overlay commands below:

Standalone mode :

[standalone@localhost:9999 /] deployment-overlay add --name=help2 --content=/help.html=/tmp/help2.html --deployments=example.war --redeploy-affected
[standalone@localhost:9999 /] deployment-overlay link --name=help2 --deployments=example.war --redeploy-affected
{"JBAS014653: Composite operation failed and was rolled back. Steps that failed:" => {"Operation step-1" => "JBAS014803: Duplicate resource [
    (\"deployment-overlay\" => \"help2\"),
    (\"deployment\" => \"example.war\")
]"}}

Domain mode:

[domain@localhost:9999 /] deployment-overlay add --name=help2 --content=/help.html=/tmp/help2.html --deployments=example.war --redeploy-affected --server-groups=main-server-group           
[domain@localhost:9999 /] deployment-overlay link --name=help2 --deployments=example.war --redeploy-affected --server-groups=main-server-group
{"JBAS014653: Composite operation failed and was rolled back. Steps that failed:" => {"Operation step-1" => "JBAS014803: Duplicate resource [
    (\"server-group\" => \"main-server-group\"),
    (\"deployment-overlay\" => \"help2\"),
    (\"deployment\" => \"example.war\")
]"}}