URL tag question

I am using Struts 6.6.0,
I am needing to generate a URL using the s:url tag that will pass a List of values (example:  myurl.action?myData=1&myData=2&myData=3)
I have:
<s:url action="myurl" var="myUrl" escapeAmp="false">    <s:param name="myData">1</s:param>
    <s:param name="myData">2</s:param>
    <s:param name="myData">3</s:/param>
</s:url>
However, the generated URL only includes myData=3.
Am I missing something?
Thanks!
Matt