Does this have any gold or brass coloured versions?

I received some coins for my collection from a passing family member. There are 2 coins that I am having trouble identifying, one of which looks exactly like the regular 1975 Silver Dollar coin but instead of looking like nikel or silver colour it looks golden or like it's made of brass or some other material. I can't find any trace of it anywhere online. I have attached a picture of it alongide the “regular” 1975 Silver dollar. 

Any help indenfitying what I have here (on the right in the images) is greatly appreciated! 

If it weights nearly the same as the nickel coin is supposed to weight and looks golden it was most likely gilded.

If it is only slightly yellow maybe the coin got heated up at some point and some nickel oxide turned a yellow hue.