Duplicate layer 'base' message error while deploying a custom module directory in EAP 6

Issue

• Getting below error while deploying custom static module.

Exception in thread "main" java.lang.ExceptionInInitializerError
    at org.jboss.modules.Main.main(Main.java:364)
Caused by: java.lang.IllegalStateException: Cannot find layer base under directory /home/aaa/my-modules/system/layers
    at org.jboss.modules.LayeredModulePathFactory.resolveLayeredModulePath(LayeredModulePathFactory.java:82)
    at org.jboss.modules.LocalModuleFinder.getRepoRoots(LocalModuleFinder.java:115)
...
...
15:49:55,527 INFO  [org.jboss.as] (MSC service thread 1-8) JBAS015899: JBoss EAP 6.2.1.GA (AS 7.3.1.Final-redhat-3) starting
15:49:55,753 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-5) MSC000001: Failed to start service jboss.patching.manager: org.jboss.msc.service.StartException in service jboss.patching.manager: java.lang.IllegalStateException: Duplicate layer 'base'
    at org.jboss.as.patching.installation.InstallationManagerService.start(InstallationManagerService.java:74)