They may be worth around 75 dollars a note. Error notes are popular with collectors and it is they that determine and drive the value.
A 1996 20 dollar bill with printing errors like the ones you described may have added value to collectors due to its rarity. However, the exact worth would depend on factors like the bill's condition and the demand among collectors. It would be best to consult with a currency expert or a professional collector for a more accurate assessment of its value.
The year should be printed on the front of the bill
The U.S. never printed any $1 bills with that date.
U.S. currency is printed in a 3-step process :The back is printed first and taken to a drying room.Next the front is printed and then allowed to dry.Last, the serial numbers and Treasury shield are printed in an overprint press.So you can see it's virtually impossible for a partialback side to be printed on the front side.I suggest you take it to a coin show and have a few currency dealers look at it to figure out what you have.
It will have the words Silver Certificate printed across the top of the bill's front. In most but not all cases, the seal and serial numbers will be printed in blue ink.
Foldover errors are very collectible, and retail at upwards of $300.
The $500 bills that were produced from 1928 - 1934 have Presesident William McKinley on the front and just a 500 printed on the reverse.
Decimal currency was introduced in Australia on the 14th of February, 1966. The One Dollar note was predominantly brown and orange in colour, had Queen Elizabeth II and the Australian Coat of Arms on the front, and Aboriginal artwork on the back. All paper money introduced a metallic strip imbedded in the paper to make counterfeiting more difficult. It was a similar size and colour to the 10 Shilling note, which it replaced. There were only two major variants of the One Dollar note - Notes printed from 1966-1972 will have "COMMONWEALTH OF AUSTRALIA" printed at the top, front and back. Notes printed from 1972-1982 will have only "AUSTRALIA" printed at the top, front and back. The Australian One Dollar note was replaced with a coin, first issued in 1984 to replace its paper predecessor.
No 1934 US $10 bills were printed with red seals. However a special series was printed with brown seals for use in Hawaii during WWII. If your bill has HAWAII printed on the front and back, please see the question "What is the value of a 1934 US 10 dollar bill with HAWAII on it?" for more information.
If it has the words National Currency on the front, like all U.S. bills prior to the 1987, it was printed in Washington DC. In 1987 the BEP opened an auxiliary facility in Fort Worth. Bills printed there have a small "FW" next to one of the plate letters.
Overprints are considered major errors. Retail prices can be in the range of $200-300.
To read the information on a twenty dollar bill, simply look at the numerical value "20" printed on the front. You can also see the portrait of President Andrew Jackson and various security features designed to prevent counterfeiting.
Authentic 10 dollar bills do not have optical brighteners. Under black light, they should not glow brightly.