A complete duplication affecting one or more of the middle phalanges of the hand. As opposed to a partial duplication were there is still a variable degree of fusion between the duplicated bones, a complete duplication leads to two separate bones appearing side to side (radio-ulnar axis) as seen on x-rays. A duplication leading to an accessory bone appearing in the proximo-distal axis on x-rays, this is actually a different entity called a pseudoepiphysis (see corresponding terms) sometimes also referred to as hyperphalangism. [from HPO]