Duplicate Patents

There are a number of reasons why duplicate patents appear in the list, here are some of the principal reasons:

• Multiple regions - A patent may originally be filed in Japan, for example, then filed in different locations around the world. So the same patent, essentially, may also have a US filing number, a European filing number and a World fining number. Perhaps to simplify at some point we could just show one version and reference any connected patents.
• Patent additions - Extensions or additions to original patents can be filed (called a "family" of patents) and these may appear the same while they actually are different in some areas.
• Pending and granted patents - Some patents originally entered as pending may also show up under granted after they have been granted. Also patents may be pending in one location while granted in another.