What's in a name?

I made a new friend a few weeks ago. Her husband is new to Brandon's squadron and they have a daughter four days older than Amelia. Another wife put us in touch and we've had playdates at home as well as the park. Today we ventured downtown (that is hilarious if you've ever been here). We were in a shop where we each made a purchase. I went first. After she paid, the shopkeeper said, "Oh, Rebecca, I forgot to get your signature on the slip." Naturally, I walked back to the counter and looked at the slip. It said "Rebecca FriendsLastName." Quoi? I was perplexed to say the least. You see, my new friend is named Annie. So...

"Oh!" says Annie, " "Rebecca is really my first name. I was gonna tell you."
"Wait. What? How is that not something you would tell me right away? P.S. We have the same name."
"No one ever calls me that."
"Okay, you are definitely weird! And now I don't trust you because all the Rebecca's I know are untrustworthy."

I think I may really like this gal.