Have you looked at imcrop()? Imcrop has an interactive mode and will output the selected RECT parameter when the appropriate syntax is used.
[cropped1 rect] = imcrop(thispict);
You can then call imcrop using that parameter
[cropped2] = imcrop(thatpict,rect);
To display the images, you could do that any number of ways.
You could use subplots or tiledlayout
or you could use montage:
or since they're the same size, you can just concatenate them and show them as one