Heres the link to coppercoins site, see if your matches any of thoses http://www.coppercoins.com/lincoln/dietype.php?date=1957&die_mint=d&die_type=do&page=0
I always post a site, this way you can look on your own, and book-mark the site for later use, good luck on coin hunting
This is a quote from doubleddie.com: "The primary characteristic of mechanical doubling is that the secondary image (doubling) has a flat, shelf-like appearance. On genuine doubled dies the secondary image is raised and rounded just like the primary image." Your image is not raised or rounded like the primary image therefore it is MD.