Since 1934-35 there have been several changes in the trademarks used by the Goebel company on M. I. Hummel items. In later years of production each new trademark design merely replaced the old one, but in the early years frequently the new design trademark would be placed on a figurine that already bore the older style trademark. In some cases a change from an incised trademark to a surface stamped version of the same mark would result in both appearing on the figurine. The former represents a transition period from older to newer and the latter resulted in what are called "Double Crown".
NOTE: It is imperative that you understand that the various trademarks have been used by Goebel on all of their products, not just Hummel items, until about mid 1991, when a new mark was developed exclusively for use on M. I. Hummel items.