The Pro-96 only allows for one priority channel in the whole radio, it is not even programmed in a bank. IOW, you could have the priority frequency something that is not programmed anywhere else in the radio. That said, priority channel usage is problematic because when you activate it, it interferes with the other scanning operations (by checking for activity on the PRI Ch every 2 seconds).
Your idea of putting a specific channel in a bank multiple times has been used in the past, but all that means is it will be checked that many times as it scans that bank. If you are concerned about missing something on a specific channel while you are scanning then use the priority function, the most you can miss is slightly less than 2 seconds of transmission and with the delay on, as long as they are talking you will maintain on it. Putting it multiple times in a bank will not give you that benefit.