Maven descriptor (META-INF/maven) duplicate entry in archive - maven

Question

I'm facing a problem with maven build. I have several ejb projects. After maven build the jar-file contains the maven descriptor in META-INF/maven twice, i.e. if I extract files to disk 7zip asks to overwrite files although extracted to a new folder. If a specify <addMavenDescriptor>false</addMavenDescriptor> in the archive-tag of the ejb plugin then the maven decriptor is still generated but only once. Is there another place where I can disable maven descriptor generation or does anybody know the reason for the duplicate generation?
Maven version is: 3.0.3
Project structure is like:
-pom
-ejb
Here is the pom.xml of the EJB module:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<artifactId>TestMavenDescriptors</artifactId>
<groupId>de.test</groupId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>..</relativePath>
</parent>
<artifactId>TestEJB</artifactId>
<packaging>ejb</packaging>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-ejb-plugin</artifactId>
<version>2.3</version>
<configuration>
<ejbVersion>3.1</ejbVersion>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.0.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>6.0</version>
<scope>provided</scope>
</dependency>
</dependencies>
Here is the pom.xml of the parent project.
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>de.test</groupId>
<artifactId>TestMavenDescriptors</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<modules>
<module>TestEJB</module>
</modules>
</project>

Answer 1

I found out that this is a problem special to eclipse version (I have RAD 8 trial) and possibily of the m2e plugin version. The above behavior (duplicate generation of maven descriptors) occurs only if I have the EJB project in my workspace added. That means if I remove the EJB project from workspace (without deleting contents on disk) such that only the hierarchal parent maven project (pom packaged) is existing in the workspace (which contains the EJB project but EJB project is then not known to eclipse) then everything works fine. Strange, isn't it?!
BTW: on current eclipse (java ee package) this doesn't occur, all fine there.