type of art which have another image behind?

Question

There is the art which have two images front and behind, so that when you look into it for several time you can see anoyher objec behind the picture.

Answer 1

are you referring to 3d imagery?
or are you talking about illusionary art,sometimes referred to as metamorphic art. this is where one image turns into another image
or you can see several hidden different images. LF

Answer 2

ambiguous figures - a type/ form of optical illusion

An illusion in which the subject or the perspective of a picture or shape may suddenly switch in the mind of the observer to another, equally valid possibility. Often the ambiguity stems from the fact that the figure and ground can be reversed.