Malaysia  Bunga Raya Series 1994 20 Cents With Mechanical Die Doubling (MDD).


Mechanical doubling is probably the most common form of doubling on Malaysia coins and the form of doubling most often confused with doubled dies, especially by those just getting started with collecting die varieties.

This form of doubling has been known by a number of different names over the years. It has been referred to as “ejection doubling”, “machine doubling”, “strike doubling”, “shift doubling”, and “shelf doubling”. If you see references to any of these, it is most likely mechanical doubling that is being referred to.

The primary characteristic of mechanical doubling is that the secondary image (doubling) has a flat, shelf-like appearance. On genuine doubled dies the secondary image is raised and rounded just like the primary image. Also, genuine doubled dies are characterized by a splitting of the serifs on letters with serifs, or a “notching” of the corners of the letters which are doubled. This splitting of the serifs or notching of the letter corners will not be found on coins with mechanical doubling.

Unlike genuine doubled dies for which the doubling is on the die itself (hence the term “doubled die”), mechanical doubling is the result of loose parts in the coining press. These loose parts allow the dies to shift slightly at the moment of impact when the coin is being struck. This slight shifting of the dies is what causes the flat, shelf-like appearance of mechanical doubling

This form of doubling is extremely common with numerous examples being produced on all denominations every year. Most serious doubled die collectors view this type of doubling as a form of damage to the coin rather than a collectible form of doubling.I am not saying that you cannot collect this form of doubling, if you are interested in it. Rather,I am saying that you should know the difference between the two forms of doubling and label them properly. Knowing that mechanical doubling is an extremely common form of doubling you also need to be very realistic about any values that are assigned to coins with this common form of doubling.

Source: Wexler's coins and die varieties.


  1. Hello admin.

    Saya kira MDD adalah mmg sgt berbeza dgn genuine Doubled Die, saya harap admin tidak mengelirukan pembaca dgn contoh bergambar yg diletakkan di dlm posting ini, kerana tiada dlm istilah Mechanical Doubled Die (MDD). genuine Doubled Die sering dikaitkan dgn variety kerana ia berlaku semasa proses hubbing. sedangkan MDD adalah berlaku semasa manufacturing dlm kategori striking error. sekiranya gambar rujukan diatas ditulis sbgai Mechanical doubling damage adalah lebih bersesuaian.

  2. Hi Anonymous,
    I am sorry and thank you very much for your kind comments. I amended accordingly.
    Hope you all will always drop by to correct me from my wrong interpretation of error coins.
    You kind contribution of comments are making my Blog better,I sincerely thank you.