This fixes an issue I encountered when I tried to create a new content t...

...ype called 'sponsorship' and to my surprise it was

not showing up in the UI, so after banging my head a couples of times on the keyboard I entered mysql console and noticed that
the node_type table actually had my newly created content type but the problem was that the 'sponsorship option' content type
had the same orig_type value as my newly created content type so drupal got confused. Anyways, this patch will prevent anyone
from entering a duplicate machine readable name on content types in which their orig_type is the same.

see https://drupal.org/node/515454 for info on this core bug