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="1024px-Another_view_from_Lahaina_at_sunset_(8705195358).jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="4369" ns="6" title="Slika:&#039;&#039;&#039;Aman&#039;&#039;&#039; antično gledališče.jpg">
        <duplicatefiles>
          <df name="Aman_antično_gledališče.jpg" user="KHvala" timestamp="2015-01-17T08:48:13Z" />
        </duplicatefiles>
      </page>
      <page pageid="3078" ns="6" title="Slika:06 cres-plavnik-krk.gif" />
      <page pageid="1140" ns="6" title="Slika:08b.jpg" />
      <page pageid="1764" ns="6" title="Slika:1.jpg">
        <duplicatefiles>
          <df name="El_Jem_Museum.jpeg.jpeg" user="Mrhar" timestamp="2014-06-01T08:03:02Z" />
          <df name="El_Jem_Museum_(2).jpg" user="Mrhar" timestamp="2014-06-01T08:32:39Z" />
          <df name="El_Jem_Muzej.jpeg" user="Mrhar" timestamp="2014-06-01T08:59:30Z" />
          <df name="El_Jem_Muzej.jpg.jpg" user="Mrhar" timestamp="2014-06-01T08:05:10Z" />
          <df name="muzej_-_pisno_besedilo.jpeg" user="Mrhar" timestamp="2014-06-01T08:45:57Z" />
        </duplicatefiles>
      </page>
      <page pageid="3309" ns="6" title="Slika:1000px-LocationAustria.svg.png" />
      <page pageid="1084" ns="6" title="Slika:1024px-20110421 Tbilisi Georgia Panoramic.jpg" />
      <page pageid="1800" ns="6" title="Slika:1024px-2012 King Kamehameha Parade.jpg" />
      <page pageid="1801" ns="6" title="Slika:1024px-2012 King Kamehameha Parade (7435788472).jpg" />
      <page pageid="2798" ns="6" title="Slika:1024px-Acropolis of Athens 01 - Parthenon.jpg" />
      <page pageid="3299" ns="6" title="Slika:1024px-Al-Hamidiyah Souq 02.jpg" />
    </pages>
  </query>
</api>