posible that someone join my server as crack?

[Dominilk]

I was looking intro my data.yml (it contain all player data for save betwen restarts)
and i see this UUID "  00000000-0000-0000-0009-01f675a9ebbf:"

im saying oh a funny UUID,
and bc beffor uuid was anoying if need tweek data it i add username to fast see to who is link
and i see "player: .Vxrtex6529" 

firt: its a imposible username it contain a " . "
second: this username is not list on namemc

can someone give me some anwser ?

Edited June 11 by Dominilk

[Dominilk]

and if ask: yes the player have more than default data, so player played on server

EDIT: i look more closly intro this data and i found out 5 player with uuid start 00000000-0000-0000-0009-01f and username start this a " . "

Edited June 11 by Dominilk