PP creates unwanted keyframe interpolation

Hi.

I´ve been trying for hours to make this simple thing work, and I dont think I know enough on the subject to fully understand what I am doing, so I hope you can help ☺

I want to slide an image into the picture, and afterwards out, with a "custom easy ease in" movement.

So I have to keyframes with the exact slide-in motion I want.

Now I would like to copy these to keyframes, so I can keep the exact movement, and just change the image position on the keyframes, so the image can slide out of the picture the same way it came in.

Problem is, when I do this Premiere adds some wierd movement on the image and some interpolation(?) between the keyframes. How do I remove this so it´s just linear, and not wierd movement?

I´ve tried right-clicking the keyframes and change the interpolation, dragging and the handles and what not, but I cant get rid of this auto-generated movement.

Thanks alot for your help