Ender dragons are super easy to duplicate on bedrock edition, and due to how buggy they are (and how laggy the dragon breath is) its a fairly easy way to break worlds and ruin the end dimension. Basically you just need to make the ender dragon fly thru a end gateway.

You can find a full replication process in this video, where i show off this bug:
https://youtu.be/y312W9CTLbk