How knowledgeable of fragrance are these guys? And particularly about those two frags? If they know frags, maybe they are a bit similar, but otherwise, I would guess that they just smelled "strong" and maybe remembered you talking about FdA. That's the only explanation I have at the moment. Did you rave about FdA earlier? Maybe they think you're like them, and wear the same thing day after day, and just assumed it was FdA.
Wow. Few of my friends even know the names of frags. At least you have 3 friends who know a niche frag!