Coinedup accesses and logs users in, via Google's unique OpenID designated to each Google account. So basically, if the PC through which you're logging in, is connected with a Google account other than yours, you will be logged in to that account instead of yours. It's not a security issue, simply because user of that computer NEVER logged out of his Google account on that computer and left logged in and that's why you were logged in directly to this account.
I thought about that. Checked google. But there i was logged in with my account.
So this can´t be the issue.
" got into another persons wallet by using a different pc"
Just another random noob kid who likely doesnt know how technology (openID) works.
Ill be the first to admit its slow as balls. They could use a hardware upgrade.