This is because you are not understanding what remap is trying to do, naming take the same footage (same frames at in and out points). So it will have to adjust both sides to make this happen.
To do what you want to do there needs to be a cut (instead of a keyframe) then you make the clip to the right 25% and it will now push everything down, since the clip is 4x as long in duration. but the clip on the right will pick up where the other clip leaves off and be at 100%. Now you can adjust the start of the first clip to be later if you need it to fit in the same time slot as before.