Some people don’t pronounce Don and Dawn exactly the same. They may pronounce the vowel in Dawn a little longer, and possibly with a little more rounding of the lips.
We have a Jocelyn and Jocelyne (aka Joss and Jossi).
I have met a guy named Sophocles Sophocles.
A close friend of mine has a younger brother named Kerry who married a woman named Kerry.
I think I’ve told this story here before. My husband swears it’s true, and his mother has confirmed.
Growing up, he had a male teacher in school whose first name was Shirley. It’s rare but not unheard of. He married a woman named Shirley … and they went on to have two children, a boy and a girl.
And they named them both Shirley.
Now that’s just freaky, because my cousin Dawn also married a Don. Do your Dawn and Don live in Minnesota, by chance?
Close enough tho 
We have a family friend whose name is Dawnald (male). He has never (to our knowledge) been involved with a female with any same-sounding name though.
Right - this varies by accent. In NY their names sound quite different, but in the midwest - not so much.
Nope - TN now, by way of Buffalo, NY. Considering the Buffalo weather tho - it might as well have been MN 
[hijack] I used to work with an older man- who was rather strange by most standards- who was named I think Joseph Mitchell or something like that. To our company picnic he brought his two brothers, who looked almost identical to him, and introduced each of them as
Joseph Mitchell.
When we were all flabbergasted, they acted as though it wasn’t very unusual (surely though they had been asked this their whole lives!?) and shrugged it off with “It’s what Mom named us…”
[/hijack]
I have a second (or something) cousin Don who married Dawn (they’re in MA).
Maternal grandparents were Eddie and Teddy (though Teddy was a nickname, short for Teddy Bear).
I’ve heard of Spanish or Italian folks using the first name Maria for all the girls, but I assume they would go by the middle name. What was that Newhart thing? “This is my brother Doug and my other brother Doug?”
My mom has a cousin Russell Russell.
heh…
George Foreman has 7 children – 5 boys named George and 2 daughters, Freeda George and Georgetta.
Famous people? Nope. But I knew a couple in Lyons, Colorado, who’s first names were LaVern (him) and LaVerne (her). I don’t remember their last name. Both were devoted activists in their little town, and the newspaper I worked for had a special style just for them – on first reference, we used first and last name; subsequent references were all first name. It was just easier that way.
My youngest step-daughter is Stacy. Her husband is Tracy.
This is totally off-the-wall, but yes, I’ve known of several couples with the same names. In the 70s, I was part of the Sikh religious group known as 3HO. When the group first started up, the teacher, Yogi Bhajan, matched up quite a few couples, many of whom he then gave new names - and usually they were both the same.
Other than that, I’ve also known a few Christopher/Christine couples who both went by Chris and Chris.
I can’t think of any personally, but the OP made me think of the WKRP episode with the Rev. “Little Ed” Pembroke, the former wrestler turned radio preacher.
Johnny Fever: Why do they call him Little Ed?
Venus Flytrap: Because his wife is Big Ed!
I know two couples who are each Carl and Carol.