The name one way mirror is misleading. You can get the one-way effect with a partially reflecting mirror and careful lighting, but there is no such thing that passes light in only one direction. Think about it. In the interrogation room you refer to, the "one way mirror" looks like a mirror from the inside of the room. Obviously it is reflecting at least some light back into the room.
What you would see if you had a interrogation room setup with the usual partially reflecting (and therefore partially passing) glass and a normal fully reflecting mirror on the opposite wall, is a series of repetitions of the scene in the room getting dimmer and dimmer as they appear to be father away.
Let's say for sake of example that the partial mirror reflects 80% of the light and passes 20%, and that the mirror on the opposite wall is a perfect 100% reflecting mirror. You are in the dark observation booth and you can see everything in the interrogation room at 20% brightness. Some light from the subject in the room will reflect off the back mirror and then thru the partial mirror. That will look like another copy of the scene (appropriately flipped in orientation) behind the full mirror. You will also see this scene at 20% brightness. The light that reflects off the partial mirror, then the full mirror, then thru the partial mirror will appear from another virtual room behind the previous, and you will see it with 80% * 20% = 16% brightness.
This phenomena repeats creating a infinite succession of virtual rooms behind the real one. Every second virtual room will be 80% as bright as the previous pair. Eventually the brightess will be so low that it will appear black to you, and the succession of virtual rooms ends in darkness from what you can observe.