Makeitstop - I knocked on the wrong door of a two family house. Since then I’ve always asked people as part of the directions if there’s more than one entrance.
My Cousin Gerda used to have the extended family over for Thanksgiving dessert–a family tradition I really miss. All the houses on her block looked identical, and it was night . . . so once we pulled up in front of a house, I rang the bell, a woman came out and said, “Pam!” and gave me a hug and took me inside to greet everyone–of course, we were a whole block away from Gerda’s.
They seemed nice, I kinda wish I’d stayed.
I had something like that happen to me once.
I was 15, sitting out in the car with 2 siblings while my mom was in the grocery store getting something for dinner. I was in the driver’s seat, my siblings were in the back. This guy opens the passenger door, slides in, and closes the door. Without looking at anyone, he starts digging under the seat, then through the glove compartment, and finally over the visor.
The whole time me and my siblings are sitting there staring at this guy with a wtf? look on our face. He gets fed up from not finding whatever he’s looking for, slams his hands on the dash, then looks over at me.
He gets this really startled look on his face, screams holy shit, apologizes, gets out of the car, and runs 3 cars down to get into another vehicle. After a few minutes he comes back, calmer, and explained what happened.
His car and our car was same make, same model, same color. Each had a dented driver’s door, with very similar dents. Both had a busted right headlight. About the only difference on the outside was the license plate, and then the only difference was 2 digits.
After he explained, I looked at his car, and darn if it didn’t look almost exactly like ours.
Early/mid 90’s - we’re doing a race in NYC. We have a block of rooms in the hotel, two to a room. Somehow I draw (really) long straw; room to myself & a great view. Finish up for the day & meet in the lobby to go out to dinner. Come back about 10:30 & go up to my room because others want to see the view. Open the door & then quickly close it. - I must be in the wrong room because there’s someone sleeping in the bed! Someone say it must be right because the key opened it; look at the key (these were the old days of actual metal keys with room # tags) & confirm it’s right. So off to the front desk to see what the hell is going on & why Goldilocks thought my bed was just right.
Apparently, while we were out to dinner one of the other guys girlfriend showed up. His roommate was moved to my room so they could have some 'lone time for the night. The kicker was I disgorged the contents of my bag on one bed thinking I’d sleep in the other one. Now I need to clean off the bed before I can even crawl in.
We were at a function at a nice eatery up on the hill where it has a nice view. As we were leaving, Kevbabe needed to use the toilet. While I was waiting for her, I was standing at the window, taking in the view. She walked up behind me and put her hand on my waist. I reached behind with both arms and hugged her, causing her to pull away. That is when I turned around and met the waitress who had been trying to nudge me away from the door to the patio that I was blocking.
My daughter did this once. Was given vague directions to a party at a lake cabin. Went to the wrong house and was playing music on the stereo while waiting for everyone to show up. There was beer in the fridge, so she was sure she had the right place.
I was standing in a breakfast buffet line when somebody came up behind me and began massaging my shoulders, something my wife does often, so I wasn’t too startled – until I noticed my wife a few feet away filling up her coffee.
I turned around, and the woman behind me went pale as ghost and stammered, “Oh my god, I’m so sorry, you look just like my husband from behind!” All I could do was laugh, which made her less mortified, and I assured her it was all good. My wife came over and said “You can’t have him, he’s mine!” and all three of us were pretty much cracking up. I did see her husband later and, yep, I could see how she made the mistake.
That’s a good policy. Jack, I keep the back door open for the cats on nice days - please ring the doorbell before you come in. 
That’s another reason I always lock my car doors - I drive a silver Corolla, just like the other fifty silver Corollas in the parking lot (I’ve decorated mine a bit, though, so I can pick it out in the parking lot).
Good way to break the ice!