(Updated and better worded version of MC-9738)
If 2 players are standing in roughly the same place and one of them is given an item there is a chance it will be picked up by the other player.
(Probably due to items being spawned at the location of the player which also causes items to not pick up if the player teleports)
Would be better/sensible to put items into the inventory rather than at the feet of the player as this is more consistent
