What is the value of a double stamped 1975 D penny?

Answer 1

Assuming when you say "double stamped" you mean "double die" [2 images of some of the details of the coin can be seen], there were no double die cents in 1975. However, that does not mean there are not coins on which 2 images of some of the details, like letters or numbers, can be seen. There is what is known as "machine doubling". This happens when the coin presses and dies do not fit together very well, usually because of wear, and when a coin is struck by the die the looseness of the machinery causes the die to bounce just a little and , in effect, strike the coin for a second time. The "bounce" strike would not exactly match the image on the coin from the intended strike and thus parts of the coin appeared doubled. Machine doubling was more common in the early 1980s but it was also seen in the 1970s. This sort of doubling has little if any numismatic value.