In response to what @maumau78 and @connseanery have brought up regarding seeing both players in Blender...
Again I apologize. I forgot to include one important step in the guide I posted. I re-uploaded it so go back and look at it for the updated guide. In so many words, the step I did not include this morning is where you go into Edit Mode, select the "UNUSED_2K20" vertex group, and shrink it to exactly ZERO (essentially reducing it to a single point).
You may be wondering why the base player's headshape etc. gets left in... It CAN be deleted entirely from the file but the game does not respond well to the actual deletion of vertices when it comes to the head. The game does not like it when you mess up the order of things in that manner. If you do, it will produce something along the lines of this picture below from encountering the same issue last year with 2K19 conversions.
I don't know how much you guys care about the nitty gritty here - but in the model file, there are 10 different sections with different types of vertex data in the model file that when parts of it are omitted, it causes problems. However, if all that data is left in there, we can instead ensure that it doesn't show up by indicating in the SCNE file that it is part of the "hidden_shader" group - which includes the hips and the feet areas. And as the name implies, these parts are invisible. So technically the vertices themselves are still there, but that's all they are... A group of invisible vertices. By shrinking them as I described above, that also reduces them to a single point and gets them out of the way for any potential edits in Blender.