问如何解决模块X的多个工件被检索到Apache Ivy中的同一文件？

EN

<!-- Ivy settings start-->

    <condition property="ivy.home" value="${env.IVY_HOME}">
        <isset property="env.IVY_HOME" />
    </condition>


    <target name="download-ivy" unless="offline" description="Download Ivy">
        <mkdir dir="${ivy.jar.dir}"/>
            <!-- download Ivy from web site so that it can be used even without any special installation -->
        <get src="http://repo2.maven.org/maven2/org/apache/ivy/ivy/${ivy.install.version}/ivy-${ivy.install.version}.jar" 
            dest="${ivy.jar.file}" usetimestamp="true"/>
    </target>


    <target name="init-ivy" depends="download-ivy" description="Initialize Ivy">
        <!-- try to load ivy here from ivy home, in case the user has not already dropped
        it into ant's lib dir (note that the latter copy will always take precedence).
        We will not fail as long as local lib dir exists (it may be empty) and
        ivy is in at least one of ant's lib dir or the local lib dir. -->
        <path id="ivy.lib.path">
            <fileset dir="${ivy.jar.dir}" includes="*.jar"/>
        </path>
        <taskdef resource="org/apache/ivy/ant/antlib.xml"
        uri="antlib:org.apache.ivy.ant" classpathref="ivy.lib.path"/>
    </target>

    <target name="update" depends="init-ivy" description="Download project dependencies">
        <!-- edited for brevity -->

        <ivy:retrieve pattern="lib/[conf]/[artifact]-[revision].[ext]" />
        <!-- edited for brevity -->
    </target>


    <target name="clean-all" depends="clean" description="Purge ivy cache">
        <ivy:cleancache/>
    </target>

<!-- Ivy settings end-->

<ivy-module version="2.0">
    <info organisation="org.apache" module="hello-ivy"/>
    <dependencies>
        <dependency org="commons-lang" name="commons-lang" rev="2.1"/>
    </dependencies>
</ivy-module>

Buildfile: C:\Users\Jansu\workspace\HelloWorld\build.xml
download-ivy:
      [get] Getting: http://repo2.maven.org/maven2/org/apache/ivy/ivy/2.2.0/ivy-2.2.0.jar
      [get] To: C:\Users\Jansu\.ant\lib\ivy-2.2.0.jar
      [get] Not modified - so not downloaded
init-ivy:
update:
[ivy:retrieve] :: Ivy 2.2.0 - 20100923230623 :: http://ant.apache.org/ivy/ ::
[ivy:retrieve] :: loading settings :: url = jar:file:/C:/Users/Jansu/.ant/lib/ivy-2.2.0.jar!/org/apache/ivy/core/settings/ivysettings.xml
[ivy:retrieve] :: resolving dependencies :: org.apache#hello-ivy;working@Jansu-PC
[ivy:retrieve]  confs: [default]
[ivy:retrieve]  found commons-lang#commons-lang;2.1 in public
[ivy:retrieve] downloading http://repo1.maven.org/maven2/commons-lang/commons-lang/2.1/commons-lang-2.1.jar ...
[ivy:retrieve] ................................................................................................................................................................................................................................................................................................................................................................................................................. (202kB)
[ivy:retrieve] .. (0kB)
[ivy:retrieve]  [SUCCESSFUL ] commons-lang#commons-lang;2.1!commons-lang.jar (1704ms)
[ivy:retrieve] downloading http://repo1.maven.org/maven2/commons-lang/commons-lang/2.1/commons-lang-2.1-sources.jar ...
[ivy:retrieve] ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (255kB)
[ivy:retrieve] .. (0kB)
[ivy:retrieve]  [SUCCESSFUL ] commons-lang#commons-lang;2.1!commons-lang.jar(source) (1819ms)
[ivy:retrieve] downloading http://repo1.maven.org/maven2/commons-lang/commons-lang/2.1/commons-lang-2.1-javadoc.jar ...
[ivy:retrieve] .........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
[ivy:retrieve] ................................................................................................................................................................................................................................................................ (518kB)
[ivy:retrieve] .. (0kB)
[ivy:retrieve]  [SUCCESSFUL ] commons-lang#commons-lang;2.1!commons-lang.jar(javadoc) (2817ms)
[ivy:retrieve] :: resolution report :: resolve 2094ms :: artifacts dl 6357ms
    ---------------------------------------------------------------------
    |                  |            modules            ||   artifacts   |
    |       conf       | number| search|dwnlded|evicted|| number|dwnlded|
    ---------------------------------------------------------------------
    |      default     |   1   |   1   |   1   |   0   ||   3   |   3   |
    ---------------------------------------------------------------------
[ivy:retrieve] :: retrieving :: org.apache#hello-ivy
[ivy:retrieve]  confs: [default]

BUILD FAILED
    C:\Users\Jansu\workspace\HelloWorld\build.xml:177: impossible to ivy retrieve: java.lang.RuntimeException: problem during retrieve of org.apache#hello-ivy: java.lang.RuntimeException: Multiple artifacts of the module commons-lang#commons-lang;2.1 are retrieved to the same file! Update the retrieve pattern  to fix this error.

    Total time: 11 seconds

<ivy:retrieve pattern="lib/[conf]/[artifact]-[revision].[ext]" />