Use the track motion. It is at the start on the time lines where the level adjustment slider is and is a small white box with an arrow in it. If you click it you can key frame where you want to adjust and just grab the edge of the box to adjust size or move.
In other words, you want to zoom-in both images simultaneously?
1) Copy Pan/Crop settings from one image to another (Paste Event Attributes)
2) Use Track Motion (two compositing childs, one parent track - use parent motion for zooming)
3) You can put your images in a separate project, add it to the main timeline, and use Pan/Crop with the nested project.