You've copied an event. Then, you've made edits to the new event's auto-responder. These edits are also being reflected in the original event's auto-responder.
Auto-responders have unique keys identifying them. When you copy an event, the new event references the same auto-responder keys as the original. Copying an event will not automatically create new auto-responders (with new keys). This is the reason for the above problem.
Philosophically, one could argue that it should create new auto-responders when copying an event. Others could argue that they want to use the same auto-responders since the event is a copy. Since it's personal preference, the solution is really just education on how it's working and how to proceed if you do indeed want new auto-responders for the new event.
If you'd like to have new, separate auto-responders for the new event copy, you'll need to delete the old auto-responders currently assigned to the new event. Then, create new ones for the new event.