What's up with cluster of users like: j_s,password4321,carolinew,colinwright,kuharich etc. https://stylometry.net/user?username=j_s https://stylometry.net/use

What's up with cluster of users like: j_s,password4321,carolinew,colinwright,kuharich etc. https://stylometry.net/user?username=j_s https://stylometry.net/user?username=j_s https://stylometry.net/user?username=carolinew https://stylometry.net/user?username=carolinew https://stylometry.net/user?username=colinwright https://stylometry.net/user?username=colinwright https://stylometry.net/user?username=password4321 https://stylometry.net/user?username=password4321 Lowest match for j_s is 0.80 and all but one is black.