All the two swap on 4x4x4 (7 cases)

The number of all the two swap on 4x4x4 is 7. I will list them all.(Case 1)







A better solution







Any second cube is not on the same side as the first one can use setup to use the case 1. (case 2)






(Case 3)





(Case 4)





Another handy way for case 4.





Case 5 is the mirror of case 2.





Case 6 is the mirror of case 3.





Case 7 is unique.