[Isaac97]

This is very much your decision. Most conversions only use a single potentiometer. However, many OEM vehicles use two; of course they are concerned about safety over millions of miles, and also could be on the hook for liability if anything bad happens.
Does your controller support two?
Have you considered buying, say, a Prius pedal? Those incorporate two potentiometers and output a 0.8-3.6 volt signal.

 

[Isaac97]

Interesting! Do you have the -P option? That determines a lot of what is possible.

The 'standard' (no -P) requires a 2-wire potentiometer; rather than needing +, -, and signal, it's just wire 1 and wire 2. Thus the controller reads resistance rather than voltage.
With -P it reads voltage from the sensor; I can't tell whether you need their pedal, does the Zilla support throttle calibration?