Hello Samson,

The only condition to get doubled registered users in the chat list is having 2 login session active at the same time, for example if users login with different browsers or access point with the same account, or if there is still an active session for a previous login so that users overlap.

You could try to reduce the parameter value
Min inactivity time to strip out users our reduce the Joomla session lifetime.

Greetings,

John