Duck laid a gigantic egg

[Debbie292d]

Double yolks is not uncommon for a duck when they first start laying. I have seen pictures of triple yolks, but have not seen that my self.
The egg with a "tail" is not normal.

Sorry to hear your duck is missing. Over the years we have had ducks end up living with our chickens. It has worked fine for us. (Duck Hens not drakes are ok with chickens)

We never found her, and she never came back. So we found Gerty a couple of friends. https://www.backyardchickens.com/threads/debbies-silkies.1612185/post-28893684