I have created two applications packaged as EAR, each has a WAR file for a web application. For each web application I have added a jboss-web.xml specifying a virtual-host. The application context for each of the webapps has been specified as "/". Suitable entries for the two virtual hosts have been added to server.xml.

On JBoss startup the following error appears

javax.management.InstanceAlreadyExistsException: jboss.deployment:id="jboss.web.deployment:war=/",type=Component already registered.
at org.jboss.mx.server.registry.BasicMBeanRegistry.add(BasicMBeanRegistry.java:767)
at org.jboss.mx.server.registry.BasicMBeanRegistry.registerMBean(BasicMBeanRegistry.java:236)
at sun.reflect.GeneratedMethodAccessor89.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:157)
at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96)
at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:138)
at org.jboss.mx.server.Invocation.invoke(Invocation.java:90)
at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:140)
at org.jboss.mx.server.Invocation.invoke(Invocation.java:90)
at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668)
at org.jboss.mx.server.MBeanServerImpl$3.run(MBeanServerImpl.java:1431)
at java.security.AccessController.doPrivileged(Native Method)
at org.jboss.mx.server.MBeanServerImpl.registerMBean(MBeanServerImpl.java:1426)
at org.jboss.mx.server.MBeanServerImpl.registerMBean(MBeanServerImpl.java:376)
at org.jboss.deployers.structure.spi.helpers.AbstractDeploymentContext.registerMBeans(AbstractDeploymentContext.java:989)
at org.jboss.deployers.structure.spi.helpers.AbstractDeploymentContext.addComponent(AbstractDeploymentContext.java:719)
at org.jboss.deployers.structure.spi.helpers.AbstractDeploymentUnit.addComponent(AbstractDeploymentUnit.java:249)
at org.jboss.system.deployers.ServiceDeploymentDeployer.addServiceComponent(ServiceDeploymentDeployer.java:62)
at org.jboss.system.deployers.ServiceDeploymentDeployer$ServiceMetaDataVisitor.deploy(ServiceDeploymentDeployer.java:150)
at org.jboss.system.deployers.ServiceDeploymentDeployer$ServiceMetaDataVisitor.deploy(ServiceDeploymentDeployer.java:141)
at org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployerWithInput.deploy(AbstractRealDeployerWithInput.java:125)
at org.jboss.deployers.spi.deployer.helpers.AbstractComponentDeployer.deployComponents(AbstractComponentDeployer.java:102)
at org.jboss.deployers.spi.deployer.helpers.AbstractComponentDeployer.internalDeploy(AbstractComponentDeployer.java:82)
at org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployer.deploy(AbstractRealDeployer.java:50)
at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:171)
at org.jboss.deployers.plugins.deployers.DeployersImpl.doDeploy(DeployersImpl.java:1439)
at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1157)
at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1210)
at org.jboss.deployers.plugins.deployers.DeployersImpl.install(DeployersImpl.java:1098)
at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1598)
at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:934)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1062)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:984)
at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:822)
at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:553)
at org.jboss.deployers.plugins.deployers.DeployersImpl.process(DeployersImpl.java:781)
at org.jboss.deployers.plugins.main.MainDeployerImpl.process(MainDeployerImpl.java:545)
at org.jboss.system.server.profileservice.ProfileServiceBootstrap.loadProfile(ProfileServiceBootstrap.java:304)
at org.jboss.system.server.profileservice.ProfileServiceBootstrap.start(ProfileServiceBootstrap.java:205)
at org.jboss.bootstrap.AbstractServerImpl.start(AbstractServerImpl.java:405)
at org.jboss.Main.boot(Main.java:209)
at org.jboss.Main$1.run(Main.java:547)
at java.lang.Thread.run(Thread.java:619)

If I modify the context-root for the web applications then JBoss starts up without any errors.

I am sorry if this is not much to go on as I am newbie to the JBoss source and wouldn't know where to start to debug the issue.