From: Somewhere in the South Pacific.
I think Footslogger's problem is what is known as the Ghost Sign-in, or double sign it. It is caused when someone has a stored cookie, containing their Log-in name and password for a site without knowing. So when they manually sign-in to a site, they are also signed-in because of the cookie. They of course don't know this, but it means that every action they perform, they perform twice.
It can get even worse; because if they forget to sign-out, and sighed back into the same site. They would be technically signed in four times, with the result that they would perform four times.
When you see the Southern Cross, For the first time
You understand now, Why you came this way