Animated GIF opens with transparent pixels in frames

I sometimes receive an animated GIF that was saved with transparent pixels in frames and Do Not Dispose such that each frame has only pixels that changed from the previous display. When opened in Photoshop the corresponding layers have transparent pixels (see attached example of two adjacent frames). Photoshop doesn't seem to deal with this situation well. I can fix it by: Delete animation, make a copy of Layer 1, merge Layer 2 onto Layer 1 Copy, make a copy of new Layer 2, merge Layer 3 onto this copy... Is there a simpler way to do this? (I can make an Action to do each iteration but haven't learned more advanced actions and scripting.)