Complex sentence: The following list contains people who have claimed extraordinary memory, but it is most likely that none of them possess a real eidetic memory as scientific attempts to find people with a real eidetic memory failed.
Split into simpler sentences: The following list contains people who have claimed extraordinary memory, but none are documented examples of eidetic memory in its narrow, technical sense. It is most likeley that none of them possess a real Eidetic Memory as scientific attempts to find people with a real eidetic memory failed.