Hi Kondou, there are a few different versions linked to at:
https://moi3d.com/wiki/nodeeditor

I think the nkallen version is an experimental version which automatically builds nodes as you run regular MoI commands. It's a more intrusive install because you have to replace all of MoI's command scripts with customized versions. That can be problematic because of potential bugs introduced (I've had at least one bug report tied to that) and not having the current version. So it would probably be a good idea to do that on a separate MoI install from the main version.

> Do I need to install both？

No, if you want to generate your own node constructs you probably want just the James version at https://moi3d.com/wiki/nodeeditor

- Michael