layers panel dosen't show all photos working on together. only one at time

when i drop a new photo into Photoshop on top an existing photo it does not show up in the layers panel with the first photo. I can click on one photoit shows up in the layer panel, but i cannot get them both to show up at once to be able to work on them. Example: I want to replace sky in one photo. When I drop a replacement sky into photoshop it will not show up in the layers panel under the first photo. They will only show up one at a time which ever one I clicked 

Check to see if you have set a filter in the layers panel and turn it off if you have. If you don't see it, show a screen shot of your layers panel.

https://blogs.adobe.com/jkost/2018/03/select-and-filter-layer-options-in-photoshop-cc.html