The pic you linked is a different concept, but what you described is possible. Same concept as a shadowban just taking it further. Testing for it would be possible too. To implement you would have multiple instances of the site (lets make 2 and call them A and B) - you would need to decide how to split users. IP address on first visit would be one way but you might want to use more advanced fingerprinting. So a first time user would be assigned to either A or B, and you would record which instance and how to identify them again if they don't have an account (by IP or whatever metric you used) This might be in a database or it could just be an algorithm that is accurate enough that you trust it to keep users in the same group if they come back later. If someone makes an account you might assign them to a group, but this is tricky because let's say you're using ip address then that user might see instance A when they load the site and then instance B when they log in if their IP address had changed for example. So that's the basic idea of how you could build this. To test if something like this is in place, you would want to log in from a bunch of different devices on different networks, and see if all the posts were the same and with all the same comments on them. You could also create an account from each device and check again on a longer term basis to see if it only happens when you get an account. Seeing some of the same users wouldn't tell you anything because you could have a user assigned to both A and B and you would probably do that with approved accounts to make sure both versions appear active. You'd need to check every single comment and you'd probably want to use a script or tool to make this part easier. That said, I would be surprised if this was happening but you never know.