When doing dual extrusion there are many ways to go about it. The basic requirements are that you have a board that supports 2 Extruder connections, 2 hotend connections, and 2 hotend thermistor connections. However, if you are using a 2 into 1 adapter you only need a board that has 2 extruder connections. We are going to go over what you need for each setup and the pros and cons of each. Personally, we prefer the 2 into 1 setup due to its ease of use but they all have their advantages and disadvantages.