I can tell the "51-d still has a bit of red on it. Your "27 is a planchet error coin. It is called a mottled woody. http://www.error-ref.com/improper-alloy-mix/
Yep, love those woodies. Kind of to the degree of that old Lays potato chip commercial where it's said that one cannot possibly eat just one Lays chip.....without immediately dipping your mitt right back into that bag for more. Well, when I get a glimpse of a quality woody, I instinctively dive into my vast pictorial cache of woodies to satisfy my urge. My lovely wife, 14 years my junior, is wise beyond her years when it comes to picking me out the perfect birthday present, as she has now bestowed a quality woody upon me for 9 consecutive years. Now if I could only entice ole' Santa to do likewise.