On topic this time, I know two Erics with the same last name who work for the same company.
I worked with a guy who had the same name as me. This confused our personnel office much more than it should have.
First and last name, only myself and my Grandmother come to mind (THAT was fun one time at the bank in the years that I lived with my Grandparents and was only straightened out by having them look at birth dates, since we had the same name, same address and the same bank… After that they started putting in our middle names.)
First names, I currently know no less than 4 James’, one of which I am related to and I have to clarify when talking with family about exactly WHICH Sherry I am talking about (my Dad’s sister or my Mom’s SIL).
Those are the main ones that come to mind.
Oh how could I forget. At my last place of employment there were three nurses with my last name, myself and two women with identical first names. example Mona Lisa Simpson, Cathy Simpson, and another Cathy Simpson. The newest hire of the Cathy’s got called Cathy-Anne which she hated, but that was the way it rolled. Once one of the Cathies got my letter from management, with very confidential information. The outside of the sealed envelope had her name, the inside of the sealed envelope had my name.
I never even got more than an Ooops, our bad, much less a formal apology.
Another one… Ive had patients on the same floor with two variations of the same name, a Mary and a Marie. One was 300 lbs and bed ridden, while the other was about 88lbs
An agency nurse almost killed the tiny one by giving her the other patients meds. The patients had their names on their doors and on wrist bands, and it was highlighted and otherwise noted on both ladies’ Medication Administration Records. (Which had pictures of the patients!) Marie was non verbal, but Mary knew her name quite well.
The agency in question was told never to send that nurse back again. I don’t know what else, if anything happened to her.
My father-in-law and my brother-in-law have the same first and last names. It’s annoying because at family parties, when my mother-in-law tells me to ask “Jim” if he wants a coffee, I’m never sure which one she means unless she says “son-Jim” or something similar. Why they don’t each use a different nickname, I will never understand.
I know a Maureen Martin, too. Weird!
I have a not-incredibly-common first name, and I rarely meet people with my name. That said, in my early 20s, I worked in an office with no less than 3 other people with my first name. Given that the whole office consisted of 20-25 people, that was pretty odd.
One of my friends named her kid the same as an old friend of mine- they’re the only people I know with that surname, and don’t know each other at all, she could have picked any other name and been less confusing, but no…
Not that I knew them all, but someone that I went to school with had been one of three girls with the same name in her old class.
Both first and surnames were very common locally, but still!
My father and his brother both married women with the same first name and middle initial. So until my uncle got divorced, my Mom and my aunt had the same name.
There is another guy who must live near me with the same first and last name…we use at least two of the same doctors! I haven’t met him, but I’ve had to clear up confusion about his existence.
-D/a, the original
When I was in college, I was active in the Theatre department, as was someone else with the same first & last name as me. For one show we were put on the lighting crew together, because the Tech Director thought it would be funny to see our names in the program together.
My name doppleganger told me he had dated a girl who had dated someone else with the same first/last name as us. He took me to a party and introduced me to this girl - her eyes lit right up when she heard my name. I guess she was working on a collection. And no, I did not.
When I was in college, I knew two guys named James Moore. I took different classes with each of them, but since they had similar majors with a few overlapping classes, it’s possible they ended up in the same class at some point. That would be confusing for the professor. 
Yes, my sister-in-law, and my niece’s wife. And they both share my sister’s maiden name.
My sister was the original Laura A. She changed her last name when she married.
My brother Richard (called Rich) married a Laura, so she became the new Laura A.
And his son, also Richard (called Rick), also married a Laura, so she’s also a Laura A.
We refer to all the Lauras by Laura + middle name.
They’re going to cause future genealogists a lot of confusion.
My father has a fairly uncommon combination of first and last names (individually each is fairly common in our region). An attorney in town had the same first name, middle initial and last name. His son and my younger brother also had the same first and last names (different from their fathers).
For some reason the attorney never bothered give clients a cell or after-hours number, so Dad would get calls from strangers announcing their court dates had been moved. For a while his response was, “Gee, that’s too bad. Why are you telling me this?”
I’ve known several.
One of my childhood friends’ mother and aunt-by-marriage both shared the name of Mary E. Hall. Confusing to the postal carrier, as they lived down the road from each other.
I graduated from high school with two Kevin Jones.
Two George Millers (unrelated to each other) have married into my family.
I once worked with a married couple, both named Trac(e)y Lawson.
Two Rick Williams - one Western European and one African-American. They were already friends and well known as “WW” and “BW” (for White Williams and Black Williams) before I met them. For a while they tried going by “Honky” and “Tonky” but they couldn’t get it to stick at all. They used to always bust peoples chops - use each others IDs, claim to be twins, and lots of other stuff; a great pair to go drinking with.
My Dad has the same name as local insurance agency. He used to get phone calls in the middle of the night saying “my basement is flooded”. Or “I’ve been in a car wreck.” In recent years that has dropped off, mainly because that company has changed the way their listing looks and my Dad no longer looks like one of their agents.
I work with (and am friends with) two people who have the same name. They are listed in the company directory with their department after their name in parenthesis. Whenever someone pages them over the intercom they have to say their name plus their department.
Everyone is used to it, so it’s no big deal. It does tend to confuse new people though.
Same firstname, tons.
Several cases of same firstname-first lastname combos, usually both names happen to be pretty common so the combo is a sort of “Joe Smith”.
I had these two classmates who were double cousins (sisters married to brothers) so their two lastnames were identical, they lived in the same village, had been born within a week of each other - and they had the same “multi-word firstname” (Miguel Ángel). Luckily one was a blonde and the other one darkhaired… so we called them “Blonde” and “Dark”. But alas, after they’d been in our class for two years we got another classmate whose name was Miguel Ángel “Dark” - ah, his family called him Michel, good… but there was already a Jesús Miguel called Michel… so Miguel Ángel “Dark” ended up being called Micheldós (Michel Two). My whole school year still wants to know what was the family of those two cousins thinking; couldn’t they have drawn straws to see who got to be Miguel and who got to be Ángel or something?
My sister-in-law, after she marries her fiancé and takes his name, will have the same first and last name as his ex-wife. So that’s interesting.
I have known three different guys named Michael Jackson, none of them in music.