Index: src/main/java/org/glassfish/weld/DeploymentImpl.java
===================================================================
--- src/main/java/org/glassfish/weld/DeploymentImpl.java	(revision 44859)
+++ src/main/java/org/glassfish/weld/DeploymentImpl.java	(working copy)
@@ -58,6 +58,7 @@
 import java.util.ListIterator;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.logging.Logger;
 
 import javax.enterprise.inject.spi.Extension;
@@ -327,7 +328,7 @@
                 + beanClass + " not found in the BDAs of this deployment. " +
                 "Hence creating a new BDA");
         List<Class<?>> beanClasses = new ArrayList<Class<?>>();
-        List<URL> beanXMLUrls = new ArrayList<URL>();
+        Set<URL> beanXMLUrls = new CopyOnWriteArraySet<URL>();
         Set<EjbDescriptor> ejbs = new HashSet<EjbDescriptor>();
         beanClasses.add(beanClass);
         BeanDeploymentArchive newBda = 
Index: src/main/java/org/glassfish/weld/BeanDeploymentArchiveImpl.java
===================================================================
--- src/main/java/org/glassfish/weld/BeanDeploymentArchiveImpl.java	(revision 44859)
+++ src/main/java/org/glassfish/weld/BeanDeploymentArchiveImpl.java	(working copy)
@@ -67,6 +67,8 @@
 import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.logging.Logger;
 
 import javax.enterprise.inject.spi.AnnotatedType;
@@ -95,7 +97,7 @@
     private String id;
     private List<Class<?>> moduleClasses = null; //Classes in the module
     private List<Class<?>> beanClasses = null; //Classes identified as Beans through Weld SPI
-    private List<URL> wUrls = null;
+    private Set<URL> wUrls = null;
     private final Collection<EjbDescriptor<?>> ejbDescImpls;
     private List<BeanDeploymentArchive> beanDeploymentArchives;
 
@@ -127,7 +129,7 @@
         Collection<com.sun.enterprise.deployment.EjbDescriptor> ejbs, DeploymentContext ctx, String bdaID) {
         this.beanClasses = new ArrayList<Class<?>>();
         this.moduleClasses = new ArrayList<Class<?>>();
-        this.wUrls = new ArrayList<URL>();
+        this.wUrls = new CopyOnWriteArraySet<URL>();
         this.archive = archive;
         if (bdaID == null) {
             this.id = archive.getName();
@@ -166,7 +168,7 @@
 
     //These are for empty BDAs that do not model Bean classes in the current 
     //deployment unit -- for example: BDAs for portable Extensions.
-    public BeanDeploymentArchiveImpl(String id, List<Class<?>> wClasses, List<URL> wUrls,
+    public BeanDeploymentArchiveImpl(String id, List<Class<?>> wClasses, Set<URL> wUrls,
         Collection<com.sun.enterprise.deployment.EjbDescriptor> ejbs, DeploymentContext ctx) {
         this.id = id;
         this.moduleClasses = wClasses;