Could you check the mint mark? If it's an S, your coin should be a proof issue. Normally proofs are hand-inspected at the mint so it's unlikely that an obvious error would be released. Plus, as a proof it should be in its original plastic mint holder. If the coin is not a proof but does have those two errors it would be hard to put a price on it without examination. You'd need to take it to a dealer who has expertise in error coins to have it evaluated in person. The bubble could be exactly that - sometimes a small amount of gas will be trapped in between the metal layers in the clad "sandwich" when they're bonded. The gas can result from contamination or other crud that wasn't removed completely before bonding. The gas can cause a bubble to appear when the coin is struck, or afterwards if exposed to significant temperature changes.
If you mean the obverse is missing? It's likely been altered, but take to a coin dealer to be sure.
Do you mean a quarter DOLLAR? Quarter eagles were not issued in 1968. And could you describe "double 'stamped"" ? (note the term is actually "struck" in coin jargon).
The obverse has a stylized, symbolic portrait of Miss Liberty, not a real person. The first US coin struck for circulation to have a likeness of a real person is the 1909 Lincoln cent.
It islikely the obverse die was filled by grease or other crud when it was struck. A very common thing. as to value maybe a dollar.
All error coins need to be seen for an accurate assessment. Take it to a coin dealer for an idea of value.
If it is a phony...about $10.00. If is a real minted coin; auctions start bids off at about $10 to $20 thousand.
The Pennsylvania state quarter was struck in 1999
The first US quarter was struck in 1796.
The first US 25 cent coin (quarter) was struck in 1796.
All error coins need to be seen. A MULE coin is a coin struck from two different dies not intended to be used together such as a dime obverse with a cent reverse. I don't recognize the term"Bubble-Head" but the planchets used for Eisenhower dollars are known to have "gas-bubbles" in some of them. Take it to a dealer of an accurate assessment.
All coins dated 1942 were struck IN 1942
Genuine double struck coins can be quite valuable. Check out the following website for examples : http://www.mikebyers.com I suggest you send large magnified pictures to Mike Byers, an error coin dealer, and see what he has to say about it. You can email him at mike@mikebyers.com Good luck!