Follow This Steps :-
1)First Download Green Kinemaster From Here
2)You Can Buy Green Screen From Here
3)Shoot 2 different videos with 2 different look & clothes with Green screen or Green wall.
4)Upload Background in Line master.
5)Upload both video as a layer .
6)Remove green colour using Chroma Key.
7)Adjust Timing & Frame
8) You Are all Set !