Users are able to logon to client machines and given the full amount of time remaining on their account regardless of a pending reservation on the client.
User1 has a scheduled reservation for PC1 for 1:00PM for 120 minutes. User2 walks up to PC1 and logs on immediate at 12:30PM and is given the full amount of time (120 minutes).
The pharos splash screen indicates that the machine is available for 120 minutes. When things are working correctly the splash screen shows the amount of time available until the next scheduled reservation (up to the max time allowed -- 120 minutes in our case).
This happens on random machines and occurs frequently.