Skeleton skull bug

...before I start, I'm not an English user so it can be hard for you to understand what I'm saying

 

After I saw update list for beta, I started my ordinary world which is creative and opened craftingtable. And I saw some skeleton skulls in item list. They randomly spread and I searched it as"skeleton skull" and I can see 5 skeleton skull(actually there are 15 ones) like image attached

Maybe it is one of minor bugs but I want it to be solved.