Performing a Clone stamp on multiple layers at the same time

[Ofnuts]

Yes, I didn't get the multiple source requirement.

So a totally different technique:

1. Copy what would have been the clone source layer over the target layer
   
2. Add a layer mask, fill with black (transparent)
   
3. Paint the mask in white where you would have cloned
   
4. When done on the first layer, do the same on other layers, but instead of painting the mask again, just re-use the mask of the first layer (on first layer Mask to Selection, on other layers: Initialize mask from selection ). merge down if necessary.
   

   

(layers shown side by side)

   

Example done on a black backdrop but this could just as well be target images.

See attached XCF.