Thank you for your reply!
I wasn‘t aware that the routings/endpoints were stored in the db.
Everytime a new Collection or single Type is created, strapi restarts it self. I assume that behind the scene there is some magic involved that the new created endpoints are somehow „registered“ in the config.
When you just copy the types in the api directory this „registration“ is missing and there fore the copied api is not exposed to the outside world.
I think the easiest way is just to recreate the api in the one click droplet.