Why Two Pass?
As payment volumes increase, you're faced with the need to purchase additional capacity in the form of an additional transport or change the workflow to maximize the machine throughput. In a conventional environment, full payments are processed at a far greater speed than keyed payments. With an 80% full payment and 20% partial payment mix, roughly the same amount of time is spent processing the two types of work. Full payments are run efficiently but keyed work is limited to the operator speed, and is far below the transport speed.

Two Pass Imaging is designed to maximize transport speed by moving the keying to Image Display Terminals (IDTs), and allowing the use of multiple key operators to more closely match the transport speed.

At first glance, passing items through the transport twice to get greater throughput may seem to be a contradiction -- in reality it is not. Two factors converge to make this possible. First, the ability to double, triple, or quadruple the number of keying operators, eliminating the bottleneck that surrounds the keyed payment that was mentioned above.

Second is the fact that all transports have two very different speeds:

1. Track speed -- the speed at which the track moves items without any devices being activated (encoder, endorser). 
2. Processing speed -- the speed the transport moves the same document with all the devices activated.