Engelhart & Cottrell

This is a great Cartes-de-Visite that depicts a young man, taken by Engelhart & Cottrell photographers in Lansing, Michigan. I'm not great at dating photos, but I think this is an earlier CDV, because of the thin card and no elaborate backmark.
When the photo is flipped horizontally, the stamp is upside down, it's kind of unique. I don't know if it was a mistake or if that's how it was supposed to be.
The photo is not identified.