> will always have a desired behavior of being deduped.

Okay, let's say people like repetition. Optional flag. Great, solved.

  > Maybe you want to separately invite people to the same thing

To a... holiday? Sorry, I already cannot invite people to a holiday in my existing calendar. I have no ability to edit the event. This capacity does not exist in my Apple Calendar nor Google Calendar and I'm not going to check that Outlook Calendar because the answer doesn't matter.

  > Maybe a user creates one event that is simply a title and a time,

Again, no need to auto-dedupe. But having collisions and requiring unique name entries is not that uncommon of a thing.

  > And this is mostly an exercise of not underestimating a "simple" change

Except to introduce your complexity you also had to increase the scope of the problem. Yeah, I'm all for recognizing complexity but come on man, we're talking about fucking Apple who makes you do it their way, by visiting 12 different menus, or the highway. We're talking about the same company who does not have the capacity to merge two contacts and only has the option "find duplicate contacts" but is unable to find duplicates despite multiple matching fields.

So what's your answer? Keep the bullshit and do not provide an option to allow merges or dedupes? Literally all the problems you've brought up can be resolved by prompting the user with a request to merge OR just giving them the ability to do so. You really think triplicate entries is a better result than allowing a user to select three entries, right click, "merge entries"? Come on...