The question was asked here already :
https://forums.autodesk.com/t5/visual-lisp-autolisp-and-general/how-to-copy-a-dictionary-from-one-entity-to-a-new-one/td-p/10465008
I think the goal OP wants to achieve is not to bind the same extension dictionary to 2 different entities, but to replace one that have this data (points) with another (block) that would be placed at the same location and inherit extension dictionary from sources... But Roy_043, I think you answered on OP's question in the title, thanks...