Thank you for the detailed post! One solution would be to use a
cutoutRectangle to cut out a section of the top imagery layer, to ensure that the bottom imagery layer is visible. This brings the bottom imagery layer to the surface. Here is a sandcastle demo that showcases this functionality:
You should be able to use this demo to get your implementation started.
What is your use case? It is not clear to me why you would add an imagery layer just to have it covered by another imagery layer. Finally, have you tried adding the imagery layers in a different order or updating their
alpha (transparency) value? Let me know if you have any other questions - I am looking forward to learning more!