Between Amy Pond of Dr. Who fame and Camryn Grimes from an American TV Soap entitled, The Young and The Restless, which is viewed by my wife.

Of course, both women are redheads and both do have some similarities that could certainly get either one a role as the other one's sister if required. Both are pretty gals never-the-less.

And these two for reference...

Yes, I also see some similarities there.

The word, Doppelganger, comes to mind as these are totally unrelated people wok strongly resemble each other.

https://www.thesun.co.uk/living/2599004/from-a-woman-who-found-her-twin-at-a-party-to-a-man-who-saw-his-double-in-a-fashion-ad-these-are-the-most-amazing-dopplegangers-ever/

There are many other sources online but this article was handy.

My sister said she saw my doppleganger in a restaurant once 

With so many people in the world, I guess there is a good chance we all have a few, but actually finding them is probably lottery odds.

Actually, I read some research on this and to my surprise, (and given the large number of people in the world), there is a strong likelihood that at least 6 other people look remarkably like or similar to you or another given person.

It's kind of like staying at a motel that used to have physical metallic keys to lock/unlock the doors. The odds of at least two or three other keys opening the same doors were quite high. Oddly, this happened on a trip that I and another colleague had taken. My friend had accidentally locked himself out of his room, leaving his key on the dresser. I was leaving my room as I met him in the hall. Upon explaining his dilemma to me, I jokingly handed him my key and said, "Here, you can try my key!" He put it into the lock and turned the knob immediately opening his door!!  He thanked me in a half-joking manner but stormed down to the lobby and demanded a new room! It wasn't that he didn't trust me but he felt that he and his belongings were not secure from anyone else.

If those odds held true that there are only so many possible combinations of keys and locks in a given number of rooms, he would never be as secure as he would have liked.

The same holds true for household door locks. There are only so many possible combinations or keys, tumblers, etc within a given brand of lock.

Getting back to the faces thing, there are only so many possibilities for foreheads, eyebrows, eyes, noses, mouth/lips, chin, facial widths/heights, hair color, skin tone, etc. It's all kind of like a giant Mr. Potato Head toy!

(Don't know if you brits had the famous Mr. Potato Head toys growing up). It was a plastic/styrofoam head and one could choose from a variety of lips, teeth, noses, mustaches (if desired), eyes, eyebrows, hats, etc. to create a large number of possible identities. Loads of fun for kids.

Only so many possibilities...and then...Doppelganger!

Now...if his name happened to be your name and he lives at your address and likes exactly the same things as you, etc. then one of you has obviously crossed over to a parallel world or through some portal..One of you please let us know how that all turns out!!

We had the Mr. Potato Head, but over here I seem to recall that it was an actual potato that you stuck the features on 

Maybe we had the budget version 

The keys thing is probably more common than we'd like to think - a finite set of variations after all.

I sometimes wonder what I am doing in the other universes 

Perhaps you should set aside some time to reach out to yourself for an update!

There's an old expression, "Get ahold of yourself!" and "Get in touch with your feelings."

How do we know which self we should use in the saying, "To thy own self be true."

Multiverse, Parallel Universes, Portals, mind-boggling for sure!

Good luck on reaching out!

Currently this version of me is sitting in a freezing surgery after having my Covid jab!

We've had two + the Booster and yesterday, we got our yearly Flu shots! That pharmacist was pretty amazing at her jab technique. We hardly felt anything at all and our arms weren't sore that evening or the next day like they felt after the Covid jabs!!

Anyhow, we should be all topped off for a while or until someone announces a newer, greater strain of malady. Then, we'll probably take some belongings and move into a cave somewhere!!