Warning! Convoluted story alert!
So. I thought I'd experiment to see if Streetpass Relay worked with my 2 3DS consoles - a Zelda 3DS and a Black 3DS (my original 3DS which I've loaned to an ultra-casual gamer in my household who only uses it to play Puzzle Bobble.)
Two days ago, I took my Zelda 3DS out with me and visited the 3 Nintendo Zones in my area. Meanwhile, I left my other Black 3DS at home and turned the wireless off.
Tonight, I took my Black 3DS out with me, waited until I was out of range from my Zelda 3DS and turned wireless back on, re-visiting the first of the 3 Zones. If I got a streetpass from my other 3DS, I'd know the Relay worked.
A green light appeared! SUCCESS!!
However, I didn't Streetpass myself - I Streetpassed someone called "Bongo"
I never expected this! I've had the 3DS since launch, and I've never streetpassed anyone in my hometown.
I was shocked! I was also slightly annoyed as the Zelda 3DS is my main 3DS and the one with all the games on. GAAAAH!!!!! But at least he had a pink puzzle piece!
Not wanting to miss out at the other 2 locations, I returned home and swapped 3DS consoles. As I did so, they passed themselves. I completed the games and got a new hat.
Intrigued, I visted the 1st location yet again only to receive another streetpass. This was from myself, yesterday - which, according to Nintendo isn't meant to be possible. But it did happen!!! It was my Mii before the new hat, wearing a different outfit - as I was 2 days ago. (In other words, it seems to think you're a different person if you buy a new hat.)
How I got Bongo the first time, I just don't know - unless he just happened to pass by just then, but the chances of that must be astronomical considering how I always take my 3DS out with me all the time and have NEVER got a single hit in my town that wasn't myself in 2 years.
Then, I headed off to the other locations. Nothing there. Oh well, can't win them all.