Shared session between two different PCs

I am developing a shopping cart for a client and I got a very strange feedback from my client. I use CakePHP and as in common practice a shopping cart is identified by a PHP session. As far as I know even on the same machine if we open two different browsers then PHP will create two different sessions as the server session is t开发者_高级运维ied to the browser's cookies.

My client said that when she tested the online store on two different PCs in her office (so obviously in the same network) all items that she has added to the shopping cart on the first computer would appear on the shopping cart on the other computer. I am wondering if that is possible at all due to specific configuration on her office's intranet? Even if it is due to the browser cache, it will not be shared between two computers?

Any thought or input? Thank you.

I strongly doubt two PCs will share the same session/cookies. If that ever happened, we'll have session hijacking commonplace across the Internet. The only thing I can think of that would lead her to believe the session is shared is when you have a buggy application that's sending the same (read: wrong) data to different users.