Multiple addnode fields fail

Issue Summary

If you have more than one addnode field in a node, they all fail.

Steps to reproduce:
create a type to be referenced, such as image
create a type to test, such as article
create an addnode field to image, called something like 'teaser image'
create an addnode field to another image, called something like 'article image'
add the article, attempt to add an image in teaser image -- it fails

Haven't tested to see if multiple addnode fields of different types also fail.