This situation troubled me since a few years when I m thinking back about it.
To make it simple, I lived for 6 years at the same place (it was few years ago, I was studying at that time ; so sometimes cominng back to family home-). It was a flat, at ground floor of a building, where there were 3 other flats. I was at the end of the corridor.
I never met neighbour front of me that is also on the side (don't know if it was even rentend). Briefly saw few times neighbour side to me (very briefly, like just some hellos at top).
However, I've met few of the ones in front of me. Actually, I m pretty sure I remember them all. At first, there was a white girl, a student. Then, there was a black girl student. And then, for longer time, a tall white guy, a psychologist. I spoke a bit more with the last one, from times to times. Glabally brief exchanges, but still there were some. I remember one day, when he forgot to close his door, I rang the bell until he comes to warn him for example.
I think not much longer after that, when leaving the flat, I came across a new guy. He was middle sized (170+sth cm), white, with a bit of reggae vibe. Chill dude.
I asked him if he was friend of neighbour (the tall dude), but then he looked at me a bit weirdly. Thorough the conversation, he told le he's living here since like 5 years.
I responded him it's impossible, there was another guy like month ago, but he looked me even weirdlier, so I didn't push the conversation more. And he looked geniuine in his expression.
That would mean he lived for as long as I did at the same place, which was absolutely impossible (could'nt be romantic partner, I witnessed a moving up of black girl with family).
From then on, on the remaining year I spent there, I saw him only as a neighbour. We talked a bit from times to times, brief exchanges, like when I asked him if he had food for a stray cat I hosted when she wanted (Catzilla, big up to you, wherever you are roommate).
This is the only bizarre thing I experienced. Something's off about it. Can't recall other weird stuff of this sort.
Not entirely sure it belongs in this sub either. Will read if anyone has similar story to share, could be interesting.