There are 4 and 3 different chip positions on our standard layout for single and duo chip race numbers respectively. This is done to ensure the optimal stacking height, so more race numbers can be shipped in the same package.
If your custom design does not leave enough room for all chip positions, the stacking height is increased and thus not as many chip race numbers can fit in the same package and the shipping cost increases accordingly. Information about the backside print for bibs and MTB numbers with transponder can be found here.