Site map module assigns random frequencies to content
Is there a way I can assign uniform frequency to all my content pages? or edit individual page frequencies? 


Not through the UI as far as I know, but it's possible in code using hook_xmlsitemap_link_alter():

function MYMODULE_xmlsitemap_link_alter(&amp;$link) {
  if ($link['type'] == 'node' &amp;&amp; $link['subtype'] == 'article') {
    $link['changefreq'] = 86400;
  }
}


$link also has a loc field which contains the router path for the node (e.g. "node/1"), although it's not ideal you can use that quite reliably to determine what specific node is being dealt with.


  What exactly is making the XML site map module assign two different sets of frequencies to the same content type?


It's intentional - the change frequency for each link is calculated dynamically by the module. I assume the idea is that giving Google an accurate change frequency is better than setting something static and then ultimately struggling or failing to live up to it in the mighty engine's eyes. Doesn't always work like that in practice, of course.