6 into 1 exhaust header clamp issue

Hi all,
A friend has a 6 into 1 exhaust on his Z1300-A5 which was installed by the previous owner. After its removal he found an additional collet on each of the cylinders' manifold. The additional collet was in some cases being squeezed out between the standard clamp and the exhaust, suggesting incorrect installation. It seems very odd for each cylinder to have just one additional collet. Presumably the additional collet was to enable the use of the standard clamp to be used. If anyone has seen this before please chip in with your thoughts. He is considering using Z650 collets, which are longer, to replace the two Z1300 collets and additional collet. Cheers and beers. Andy