I believe at least some of the pictures of sekaninaite from Dolní Bory pegmatite present other minerals instead.
Photo ID: 219664 - definitely something else. In case there is a sekaninaite on the other side of the sample, it might be product of sekaninaite decomposition along (001) plane, probably a mixture of chlorite and siderophyllite
Photo ID: 150948 - totally altered sekaninaite, i.e. pseudomorphose (muscovite, clay minerals, rarely feldspar) after sekaninaite
Photo ID: 326599 - it is a problem to tell what is on the picture thanks to its poor quality actually
Photos ID: 23397 & 23398 & 150947 - The same as for picture 219664. Those are sekaninaites for sure, but in all cases the picture present just decomposition minerals along (001) planes and not the sekaninaite itself. I am not sure if they really belong to the gallery of this mineral, If yes, their description should be changed.
Keep in mind that sekaninaite should be deep blue to violet vith vitreous lustre. Other cases (specially at Dolní Bory) are alteration product, which are found very often.