You can find the issue on Github.
If the user has recently opened a ticket the user profile will open, if the user can not be identified or didn’t have any recent activity then a new ticket is opened.
If the user profile opened and you want to create a new ticket you just have to open the action menu on the top right.
To shed some further light into this topic.
If you run the following command, you can technically disable this behavior. This means you will always get the new ticket dialogue.
rails r "Setting.set('cti_customer_last_activity', 0)"
By default this setting is set to 30.days - above value is in seconds.