I get a lot of requests to stamp on both sides of an item. I thought I'd share a an example of why I don't recommend it for most of the pieces I create.
The fact that every letter and/or design is individually placed and hit to create an impression makes hand stamping unique.
When the hammer hits the stamp, the force of the stamp on the metal moves the metal. It moves it to the sides, all around the stamp, and down into the bench block. Evidence of that downward force if left on the backside of the blank.
Most of the metals I use aren't thick enough to accommodate stamping on both sides - although I do have a few item that are thick enough. And while not every item I stamp turns out exactly like what is below, most do show this evidence of the hammer strike - which would definitely distract from anything stamped on top or around it!