Multiple dates token for auto node title
You could use the following code snippet in your auto_nodetitle configuration.
Don't forget to select the option "Evaluate PHP in pattern.".
And replace the field_date_multiple with your own field's machine name.  

Hope this helps!

&lt;?php

$dates = array();
foreach($node-&gt;field_date_multiple[LANGUAGE_NONE] as $date){
  $dates[] = date('j-m-Y', strtotime($date['value']));
}
echo implode(', ', $dates);

?&gt;