Looks like an added D to me...Coin is to nice to have a mint mark which is that mangled on a coin which is know to have been faked for many years... Coin is real, mint mark is fake...
In david lawrences complete guide to washington quarters it says the only way to be 100 percent sure is to send it to a tpg because they magnify the coin by 300X zoom and look to see it it is soldered on. It also says there are some incredible fakes!!!