So… he’s a troll?
I keed, I keed! 
For example – in the case I mentioned above, he was a WWII veteran.
Make no bones about it, we will get to the bottom of this.
What is the big deal? You are dead…so what if you are at the “wrong address”? I mean, if they aren’t going to exhume you, who cares? In colonial-era grave yards, most of the headstones have been moved.
Which makes locating somebody difficult.
What’s the big deal? Well, you might want to ask the surviving family members. And this isn’t the colonial era.
My ex-Darling Marcie’s father died a week ago. He joined the Marine Corps the day after the attack on Pearl Harbor. His ashes were sent to Arlington for internment; I would be enraged and she would be broken hearted if they were treated less than respectfully.
Jokes about this matter are inappropriate.
These don’t sound like anything that isn’t fairly common in most cemeteries.
My uncle, after retirement, was the grave-siter at the town cemetery in a mid-sized town in rural Minnesota. He mentioned all the first 3 as common in the cemetery, especially on older graves. The fourth one didn’t happen, just because at that time, cremation was almost never done in that town.
It was quite common to find that an ‘empty’ spot in a family plot was not actually empty, and that the empty spot was elsewhere in the section. And any records mare than about 40-50 years old were either inaccurate, vague, or no longer legible. And this is in a cemetery considerably younger than Arlington National. So it’s nothing unusual, I’d think.