Event dispatchers (i.e. delegate property values) are currently copied to the new instance when users copy/paste/dupe actors.
However, this means that if you have an instance whose dispatcher is dynamically bound to some event on another instance (i.e. via dynamic binding), duplicates end up being bound to the same event(s). The only way users can clear the binding from the duplicated dispatchers is to redirect the dynamic binding to each duplicate instance and then clear it. Deleting instances with bound events also can leave dispatchers with stale bindings to deleted instances.
Both of those seem like potentially unwanted behavior; we should probably be clearing those out on copy/paste/duplicate and/or when bound instances are deleted.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-151807 in the post.