Reciprocal relationship fields render empty dropdowns

Hi Anh, a while ago I wrote to you with an idea about reciprocal relationships. The fields look great, but I ran into an error.

Seem that as many dropdowns are being rendered in the reciprocal fields as there are entries of that ID in the FORM column of the mb-relationships table.

So, if you only have posts_to_posts relationships you don't notice it. But if you add relationships posts_to_pages empty dropdowns will also be rendered by the entries of the cross relationships with pages.

I was planning to add this feature to some customer sites next week, so hopefully it will be a quick fix and you can help me. Thank you