Zufallsbegegnung, chance encounter, is as close as we can get to it, I think. Germans don't dress to impress. Look at us. I mean, look at us. Norm core to the max. If you are caught wearing the same shirt twice on different days, people tend to think you are merely handling limited resources responsibly.

That sucks the first time.
But you get over it.

I have 15 identical black t-shirts.
When somone asks, "Do you only have one shirt?"
I reply "Yah! It's so comfortable I got 15 of them!"

The word is "coincidence."

I don't have a word for this, but:

I can make up a compound word in Swedish for you. Osannolikhetsförlägenhet. Osannolik means improbable. Förlägenhet here means an embarrassing situation. So the word would mean something along improbability-embarrassment-situation.

I hate that. So much so, that when I do get a chance to see my friends I haven't seen in a while, I always try to remember what I wore last time and avoid it.

Does the word need to convey "Passenger 57" and "MacGillicuddy" too?

I didn't find a word that on its own echos this exact situation. However if you leave out the details, you won't need a lot of words either, e.g.:

Oh yeah, awkward coincidence the other day — I ran into Sebastian McGillicuddy wearing the same T-shirt as last time lol. Hate when that happens.

But it's certainly a more interesting and vivid story with the details you gave us. Much like Michael McGillicuddy's infamous 'Genesis of McGillicutty' promo :)

Also not what you're looking for, but it may scratch some of the itch: déjà vu

That is, (you think) you're inducing a sense of déjà vu and disgust within Sebastian.