When 2 or more households have the same name, an individual can only be linked to the first household in the drop down list.
Create a new individual, click on "Use household address", then "Use existing household". Type in household name, and find two households with the same name but different addresses. Pick the first one and it works fine, but if you pick any other household name, the contact will be saved with a link to the first household on the list. You can't save it with any household other than the first one in the drop down list.
Confirmed on the demo site with this contact: http://drupal.demo.civicrm.org/civicrm/contact/view?reset=1&cid=141
Try to choose "Bonnie and David Jones, 123 Main Street". but it will be saved with "Bonnie and David Jones, 44 Carroll Avenue".