removal of identical objects in two images

[hawkeye]

hi,
i'm searching for a plugin or a method to remove objects which are identical in two or more images.

These are images from a flow-through cell. There are droplets of isooctane in water. I want to measure these droplets and want to create a droplet size distribution. For this i take every second a picture. You see that there are some droplets which adhere at the window. These droplets i want to remove automaticly so that i dont measure them.

thanks for help