Maven assembly : add different version of the same artifact

I found a solution by using maven-dependency-plugin to copy resolved pom dependencies and additional jar.

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.1</version>
<executions>
    <execution>
        <id>copy-dependencies</id>
        <phase>package</phase>
        <goals>
            <goal>copy-dependencies</goal>
        </goals>
        <configuration>
            <outputDirectory>${project.build.directory}/lib</outputDirectory>
            <overWriteReleases>false</overWriteReleases>
            <overWriteSnapshots>false</overWriteSnapshots>
            <overWriteIfNewer>true</overWriteIfNewer>
            <includeScope>runtime</includeScope>
        </configuration>
    </execution>
    <execution>
        <id>copy-model</id>
        <phase>package</phase>
        <goals>
            <goal>copy</goal>
        </goals>
        <configuration>
            <artifactItems>
                <artifactItem>
                    <groupId>my.test.pkg</groupId>
                    <artifactId>my-model</artifactId>
                    <classifier>server</classifier>
                    <version>1.0.3</version>
                    <type>jar</type>
                </artifactItem>
                <artifactItem>
                    <groupId>my.test.pkg</groupId>
                    <artifactId>my-model</artifactId>
                    <classifier>server</classifier>
                    <version>1.1.0</version>
                    <type>jar</type>
                </artifactItem>
            </artifactItems>
            <outputDirectory>${project.build.directory}/lib</outputDirectory>
        </configuration>
    </execution>
</executions>

Now I just have to add the following lines in my assembly xml

    <fileSet>
        <directory>${project.build.directory}/lib</directory>
        <outputDirectory>/lib</outputDirectory>
        <filtered>false</filtered>
        <includes>
            <include>*.jar</include>
        </includes>
        <fileMode>0600</fileMode>
    </fileSet>