@Beatlefreek They are not "additional amps". There are 36 banks: 1A,1B,1C,1D,2A,2B...9C,9D. Banks hold presets. Any bank can have a preset, which selects one of the amps. When you choose a bank and an amp gets selected, you can now turn the "amp models" knob to select a different amp.
When you turn the "amp models" knob without pressing "tap" at the same time, you select one of the 1-16 amps with the name written around the knob, such as #1 "Line 6 Clean", #2 "Line 6 Cruch", ..., #15 "Fuzz Box" or #16 "Tube Preamp". Now, if you press and hold the "tap" button and select #1 "Line 6 Clean", you're really selecting #17 "Line 6 Twang". In fact, the chart above for amps 17-32 reads as #17 "(Line 6 Clean) Line 6 Twang" and #32 "(Tube Preamp) Jazz Clean". This means that if you want to select #17 "Line 6 Twang", you press and hold the "tap" button and select "Line 6 Clean" on the "amp models" knob. For #32 "Jazz Clean" you press and hold the "tap" button and select "Tube Preamp"