There is only one store account module installed and it is on the store page.  The admin module points to the store page.  There is another page with the admin module, which has admin access only.   I think the problem may be with the way the cookies work - it seems that they are  keyed to the client computer as opposed to being keyed to the particular user.

I think it is an issue with "less-than-optimum" design.  Different users are distinguished in DNN by Login-id, not by the computer that they are using.  Suppose you have multiple people using the same computer, or that you have one person who has both a business account and a personal account.  For a comparison, log into Amazon or e-bay with two different id's without closing the browser and see how the account information is tracked.  On most sites, you can start an order on one computer, then log in on another using the same Login and the account information, often including an  "un-empty" shopping cart.

All I did was append the userId to the end of the cookie name. So far so good.

I went  into the currentcart class in the catalog namespace.  I then appended the following in the setCartId & getCartId methods.

 HttpCookie cartCookie = new HttpCookie(CartCookieName + portalID.ToString() + "_" +DotNetNuke.Entities.Users.UserController.GetCurrentUserInfo().UserID.ToString());

This makes the cart unique to the user on the same computer. It's quick and dirty. A long term solution is to store the cart session info in the database.