Why exception during deploying second war on JBoss?

[camillelola]

I am new to JBoss. I have a WAR running on JBoss 5.1, say First.war, on port 8080.

I want to deploy another war on the same JBoss instance. While deploying the second war I get the below-mentioned exception

*** DEPLOYMENTS IN ERROR: Name -> Error

vfszip:/jboss/jboss-eap-5.1/jboss-as/server/default/deploy/SECOND.war/ -> org.jboss.deployers.spi.DeploymentException: Error deploying: persistence.unit:unitName=#uPortalStatsPersistence


DEPLOYMENTS IN ERROR:
  Deployment "vfszip:/jboss/jboss-eap-5.1/jboss-as/server/default/deploy/SECOND.war/" is in error due to the following reason(s): java.lang.IllegalStateException: persistence.unit:unitName=#uPortalStatsPersistence is already installed.

at org.jboss.profileservice.management.client.upload.StreamingDeploymentTarget.invoke(StreamingDeploymentTarget.java:312)
at org.jboss.profileservice.management.client.upload.StreamingDeploymentTarget.start(StreamingDeploymentTarget.java:189)
at org.jboss.profileservice.management.client.upload.DeploymentProgressImpl.start(DeploymentProgressImpl.java:232)
at org.jboss.profileservice.management.client.upload.DeploymentProgressImpl.run(DeploymentProgressImpl.java:89)
at org.rhq.plugins.jbossas5.util.DeploymentUtils.run(DeploymentUtils.java:155)
at org.rhq.plugins.jbossas5.AbstractManagedDeploymentComponent.invokeOperation(AbstractManagedDeploymentComponent.java:162)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.rhq.core.pc.inventory.ResourceContainer$ComponentInvocationThread.call(ResourceContainer.java:525)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: org.jboss.deployers.client.spi.IncompleteDeploymentException: Summary of incomplete deployments (SEE PREVIOUS ERRORS FOR DETAILS):

Thanks & Regards

Camillelola