Caused by: java.lang.RuntimeException: java.lang.IllegalStateException: Duplicate Filter registration for 'springSecurityFilterChain' - jboss7.x

Question

I'm trying to implemenmt Spring security with Oauth2 for Rest API.
well I have successfully implemented this. and everything was working fine.
but then I put 'jboss-deployement-structure.xml' in WEB-INF folder
and suddenly Im getting this Exception: Caused by: java.lang.RuntimeException: java.lang.IllegalStateException: Duplicate Filter registration for 'springSecurityFilterChain'.
I have done some debugging and found out that 'onStartup()' method of 'AbstractSecurityWebApplicationInitializer' is getting executed twice (after I added 'jboss-deployement-structure.xml')
so this is attempting to add same filter twice. and hence the exception
but I dont know why this is happening and how to solve this.
please help
My web.xml:
<display-name>Restful Web Application</display-name>
<servlet>
<servlet-name>mvc-dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>mvc-dispatcher</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value> /WEB-INF/mvc-dispatcher-servlet.xml</param-value>
</context-param>
My mvc-dispatcher-servlet.xml:
<?xml version="1.0" encoding="UTF-8"?>
http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">
<mvc:annotation-driven />
<context:annotation-config />
<context:component-scan base-package="com.clickawaiter" />
<bean id="customerPortalController"
class="com.clickawaiter.customerportal.controller.CustomerPortalController">
<property name="merchantServiceImpl" ref="merchantServiceImpl"></property>
</bean>
<bean id="merchantServiceImpl"
class="com.clickawaiter.customerportal.serviceimpl.MerchantServiceImpl"></bean>
<bean id="userService" class="com.clickawaiter.security.UserService">
<property name="dataSource" ref="dataSource"></property>
</bean>
<bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:jboss/datasources/CAW_DS" /> <!-- value="java:CAW_DS" -->
</bean>
<bean id="transactionManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource" />
</bean>
My WEbAPplicationInitializer:
public class SecurityWebApplicationInitializer extends AbstractSecurityWebApplicationInitializer{
}