When I open/close my furnace (just coal burning) and when open /close chest the toolbar changes each time, and will have 4 of one of my items listed and 2 of a 2nd item listed, so instead of sword, axe, shovel, pickaxe, etc. I will see, Sword, axe, shovel, shovel shovel shovel, etc

Each time I open/close a furnace/chest, the items that are duplicated switch to something else in my inventory.

I tried opening my previous world and same thing happens. Very strange, never seen this before.

Added photos. Only thing I did between photos is open/close furnace.