You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allimages gaicontinue="003a_MA453Fall2008walther.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="7126" ns="6" title="File:-11.JPG">
        <duplicatefiles>
          <df name="-11.jpg" user="Wang321" timestamp="2009-07-29T21:39:39Z" />
        </duplicatefiles>
      </page>
      <page pageid="7131" ns="6" title="File:-11.jpg">
        <duplicatefiles>
          <df name="-11.JPG" user="Wang321" timestamp="2009-07-29T21:15:49Z" />
        </duplicatefiles>
      </page>
      <page pageid="10620" ns="6" title="File:.QE 11 CS5 2 a sol2.PNG" />
      <page pageid="719" ns="6" title="File:001 MA453Fall2008walther.jpg">
        <duplicatefiles>
          <df name="Image001_MA453Fall2008walther.jpg" user="Maintenance script" timestamp="2009-01-08T14:38:39Z" />
        </duplicatefiles>
      </page>
      <page pageid="720" ns="6" title="File:001a MA453Fall2008walther.jpg">
        <duplicatefiles>
          <df name="Page1_MA453Fall2008walther.jpg" user="Maintenance script" timestamp="2009-01-08T14:38:40Z" />
        </duplicatefiles>
      </page>
      <page pageid="8908" ns="6" title="File:002.png" />
      <page pageid="738" ns="6" title="File:002 MA453Fall2008walther.jpg">
        <duplicatefiles>
          <df name="Image002_MA453Fall2008walther.jpg" user="Maintenance script" timestamp="2009-01-08T14:38:38Z" />
        </duplicatefiles>
      </page>
      <page pageid="795" ns="6" title="File:002a MA453Fall2008walther.jpg" />
      <page pageid="8909" ns="6" title="File:003.png" />
      <page pageid="731" ns="6" title="File:003 MA453Fall2008walther.jpg" />
    </pages>
  </query>
</api>