Currently, if a Tech clicks on a ticket link in an email and they aren't the client, and they left their WHD session in their browser in Client mode (because they were submitting a ticket themselves using the Client interface), WHD tells them that it can't open the clicked ticket link because it belongs to another Client.
WHD should be smart enough to know that a technician in Client mode is linked to a Technician record and just auto-switch to Tech mode and bring up the ticket, instead of throwing that silly error. Yes, there are ways around it, but it's an annoyance that shouldn't be in the product.