Seeing other players into multiplayer

me and my friend were playing on the snapshot multiplayer and we found this.

while im watching my friend hold a pickaxe for example. on his sight he holds nothing until he joins back again or respawn/go to the nether etc..
I cant see other players use other items on their hotbars but the one they were holding when they joined the game.
same with armor.

its like a character updating glitch or freeze.