Farmbot Site vs Technical drawing/BOM

I noticed there is a confusion regarding the hardware necessary for the project.
In the Electronic part of the BOM section in the website, it is suggested that 4 motors are necessary but just 3 encoders and their cables are recommended; ( )

In the 3D drawing and BOM it appears a complete set of 4x motor-encoder-cable is necessary because the X horizontal axis has two motors. It would be better to clarify a 4x set is necessary with just different cable length.