The area of ghost image removal is a very vast research topic. For effective ghost image removal, there are many methods based on how the ghost image came in in the first place. To remove the ghost image which comes due to image subtraction, and if the object is always brighter than the background, the ghost will occur in -ve values. with this info you can remove it.
Or if you know the direction of the moving object, you know which part is object and which part is ghost. Based on this information, you can remove.
These are two very basic methods. Multitude of methods are available in literature. Google would help you in that.