Rails - Apr 2006 - Model in two different parts of the app.

I have a doubt about using models.

I have a application with two parts. The first is a login system to 
users, and the second is a administrative interface.

The administrative interface I create in a directory called admin
Both parts use the model User. Can I put the model user only in the 
model directory or I should duplicate it in the /models/admin/ too?

Thanks in advance.

Fernando Lujan