I listed 3 or 4 references and gave them all a courtesy call, to let them know that I used them as a such. I also told them that they may need to provide one more reference on my behalf, not previously mentioned. The phone call went like this:
"John, I used you as a reference. They will need to to give one more name. Sorry, I used Chris as one too, and he is going to give them Terry's name as a follow up. Sorry, Joe is going to give them Sarah's name. I haven't used Charlie yet, you could give them his name."
I would think they would understand that some of us only have so many close friends.

There are a lot of people I could give, but there aren't that many that know me intimately enough, that I or they would feel comfortable as a reference.
The word intimately was used loosely. Don't get any ideas.