Click see inside and both sprites have a variable that no other sprites or stage can have! Although only Sprite1 can change the shown variable's value, it’s weird! Also the variable's value can be changed in Sprite2 but it will not be on the shown variable! That means they are still 2 separate variables but when either one of them is shown it only shows the one variable! (Sprite1's variable) There must be a block with the variable inside of Sprite2 or it will disappear in the editor of Sprite2 after you go into another sprite or stage and back!
Nothing!