记住个人资料Cookie?

I'm building a quick application for some data-vis, I need to let users log in from my local machine and then log out, allowing the next user to log in. However, every time I log in and then out of the application, when I try to log in again the application remembers that I logged in as the previous profile and auto logs in the last user. Is there a way to keep this from happening?

I am using the PHP SDK and using $facebook->destroySession(); in my logout.