...but it's even better from the back!
In 1943, Hungary issued a series of stamps featuring historical heroes. The 4f value features Janos Hunyadi, a general and Governor of Hungary in the 15th Century.
After the end of World War II in 1945, the stamps were overprinted with new values. The 4f (forint) value was overprinted three times, with this stamp being the third overprint, 10f on 4f in carmine, SG800 Scott 657. Numerous overprint errors exist on this provisional issue, and it's a minimum value stamp in all catalogues.
In 1946, the Hungarian currency, the Pengo, collapsed, and Hungary went through a period of hyper-inflation.
Reminiscent of Germany in the early 1920's, stamps with a face value of 500,000 billion pengos were issued during 1946, before the currency reform later in the year. Prior to the issue of the high face-value stamps, remaining stocks of low face value definitives were overprinted with a code, with the stamp being sold at the relevant rate for that code on a given day. The modern equivalent would be the "Forever" stamps.
In this case, our stamp was overprinted with "TI. 2.", which was an abbreviation for "Tavolsagi level", or "Inland letter", thus becoming SG890, Scott 811. I'm assuming that the "2" represented a different rate, but would appreciate feedback on this.
So there we have a stamp overprinted twice, telling the story of the collapse of an economy after a long and bitter war. The story should end there. That is, until you turn the stamp over.
The back of the stamp shows a full, and perfectly aligned, offset of the 1945 provisional overprint. As noted, there are numerous overprint errors on these stamps, but this is the first offset that I've come across.
Interestingly, the offset was there when the second overprint ("TI. 2.") was applied in 1946. Understandably, quality control may have been lax at the time, but I think this is a desirable little item. Being in MUH/MNH condition, the offset has been perfectly preserved.
There's a lesson here, don't ignore common stamps. They can often tell a fascinating story, and have hidden secrets (and don't forget to turn them over!)