Users auto logging into OTHER users accounts

I am not sure how this is happening but multiple users have reported that sometimes they go to our cart and are logged in as someone else.

How is this possible?

How can we prevent it?


P.S. Store is closed due to this issue.

Most likely the User ID Keys and User Profile keys are mismatched.

Resulting in each pair being created as

User Information : Table x Key 1

being called as:

Table B Key 1

Table A Key 2