bug with a slime block and sticky piston

I set a slime block on top of a sticky pistion and hooked up a redstone clock to it and placed blocks on the top and sides of the slime block and it created duplicated blocks of the exact same type on the ground when the piston retracted (the piston was faced up to the sky). Also the side textures of the block went on top of the block when the piston retracted (i was using sandstone). And finally sometimes the texture of lava would come out of the blocks when i broke them.