I am wondering what might be the best way to describe someone whose surname and given name could both be interpreted as a first name.
For example: Kyle Maxwell, Duncan Kennedy, Wilson James.
I don’t think I’ve heard it described as anything other than ‘two first names’.
Plus, couldn’t just about any name be interpreted as a first name? Some of the OP’s examples are more commonly or more traditionally last names that have been used as first names. (For instance, was anyone ever given the name “Kennedy” before JFK’s presidency?)
No one in the OP was given the name Kennedy. There was a Kyle, a Duncan and a Wilson. Am I missing something and if so, what?
I was in the Army with a guy named Smith Thomas. Seriously. Since you get called by your last name in the Army, master sergeants and officers wandering casually by would always want to know why we were calling him by his first name. One of his sergeants could never get it straight in his head and always called him “Smith.”
There is an actor named Keith David and another one named David Keith.
“Kennedy” was chosen as a given name for lots of newborns during / after JFK’s presidency. Prior to that almost nobody had that as a given name. IOW, that name became repurposed from being exclusively a family name to also being a given name.
Thudlow’s point being that what we think of as a typical family name, or a typical given name, is completely arbitrary and changes over time. To the degree that’s true the OP’s question is mostly meaningless. *Any * complete name can be seen as a combo of two names either of which could reasonably be a family name and either of which could reasonably be a given name.
e.g. Taylor was unheard of as a given name in my childhood back in the 1950s. Today every elementary school in the land is positively lousy with cute little Taylors running around squealing at one another.
In countries with formal lists of legally acceptable given names the situation is quite different. The USA is past that silliness and if some ethnic groups are taken as thought leaders on this, soon enough every possible combo of pronounceable syllables will be a valid name belonging to somebody.
From the world of literature, we have a family named Major who named their son Major Major … who then went on to become a Major in the Army Air Corps in WWII …
Major Major Major Major …
Fulham FC, a few years ago when they were a Premiership club, had a player called Collins John and at the same time a player called John Collins.
When Bruno Hauptmann (Lindbergh baby kidnapper) was in the German army, his commanding officer, a captain (Hauptmann in German) asked Bruno his name. He replied “Hauptmann, Herr Haumptmann”. The captain got mad, figuring he was being mocked.
“Kennedy” was one of the OP’s examples of a surname that could be a first name. Beyond that, LSLGuy explained my point quite well.
I know a musician in North Carolina named Jones Smith. It’s not a nickname, Jones is his real first name. His dad’s nickname is “Snuffy.”
In the world of politics, there’s Ayn Rand Paul Ryan Costello.
In my family, and many others, I suppose, there was a tradition to use the mother’s maiden name for the child’s middle name. This practice could easily result in last names being cycled into first names.
In some parts of the USA, it used to be fairly common for the mother’s maiden name to be used as the child’s given name. Especially if the mother’s family was richer or higher-status than the father’s family.
“This is my friend, Vanderbilt Jones.” 
In the college rooming house where I lived back in the day, we had one Mark Gary and one Gary Mark.
I’ve known several of John Nelson and one Nels Johnson.
I met a girl who had the first name of Smith.
It will probably come as no surprise the first names of Rey and Kylo have shot way up in popularity for babies this year.
Meet the Press changed hosts from David Gregory to Chuck Todd.
The popularity of the first name Kennedy:
A very slight bulge in the early 60s as a boy’s first name, although it never reached higher than the 733rd most popular name for boys, but in the current time, among girls, it’s the 64th most popular girl’s name:
http://www.babynamewizard.com/voyager#prefix=kennedy&sw=both&exact=false
<Café Society>
It is interesting that this shows up in comics:
Bruce Wayne
Clark Kent
Peter Parker
Lex Luthor
Wilson Fisk
</Café Society>
Brian
Funny, I was thinking about this the other day and how many people who I know like this. It’s very common!