Forms overwriting CRM records

Here's the scenario:
A user is logged into a secure zone on a device - let's say a desktop in their home.
They browse a SG site while logged in. They close the browser, and a second user in the house - say their mother comes to the same site.
The original user is still logged in, and the second user fills in a form on the same site, entering their name and email.
Even if it's just a simple form, with no SZ access granted, or payments or anything complex, here's what happens.
Siteglide overwrites the CRM record of the original logged in user. That record disappears in the CRM, and is replaced by the second user's account.
If the first user fills in another form, they will be recreated in the CRM.
This can basically happen in any scenario where multiple people are using the same device on the same site (school, workplace, home).