Likhitha,

The images you see in a mirror depends on where the eye happens to be.  If the eye is between parallel mirrors then it will see infinitely many images of itself (theoretically).  With a periscope, the eye looking at the bottom mirror from the side, so that it cannot see itself.

Chris

Likhitha,

They would if they were large enough, or facing each other directly. As the purpose of a periscope is to create a displaced image (and usually to do so without being too obvious) the mirrors are small and offset.

RD