Double Reference

Provides a single field item that contains two entity reference fields.

One field is the primary that uses all the normal entity reference field forms, the other is an attached field which has most, but not all, of the same options. The two fields work together to form one field.

Notes:

• The two fields do not interact. That is, changing the value in one does not affect the value in the other. This could be done with a new field widget if someone wants to provide a patch.
• The attached field uses the default referencing method, nothing fancy like views or entity browsers. The primary field can use everything an entity reference field normally does.

Similar modules:
Double Field - Does not work with references and references are complex enough that it would have been difficult to add it as a patch.
Reference value pair - Only one reference and I needed two.

Acknowledgements:
Thanks to Lullabot for their article that helped me with the initial customization that turned into this module.
Thanks to Mediacurrent, my employer, for providing internal time to work on it when I ran out of weekend.