Above cover has 1969 Gandhi stamp of Germany valued 20 pfennig (00.20 German Mark). Mark coins and banknotes continued to be accepted as valid forms of payment in Germany until 28 February 2002 and after that it was all Euro which started from Jan. 1, 1999.
So do you think above cover is valid?
Also I am not sure how this cover with invalid stamps for postal use has special cancellation from Germany during INDONESIA 2012 World Stamp Exhibition.
But I think this are not valid stamps.!! It would be OK if there was regular postage stamp along with 1969 stamps from Germany or any other country but I am not sure whether this cover can be consider as Error or Rare or Unique or Worthless.!!
Following is screenshot from eBay were seller "sydneystampcentre" was selling this kind of cover for $8 starting price.
Recently I saw cover with USA 1961 Gandhi Stamp with 1969 Gandhi stamp of England (Dual country stamp on cover) which will be real philatelic cover and I think it's OK until it has valid stamp from posting country.
But guess what this cover was also not sold even though it has dual country stamp because it's easy to make this kind of dual country cover from USA as it has still valid Gandhi stamp. (I have made this kind of covers for myself!!)
So I am not sure what are all dealers/collectors are trying to do. I think they just want to make money as fast as they can by making this kind of cover and some new collector will think it's unique or rare and will buy it.!!
Gandhi Stamps Club.