Jesika H

Happens for me in 1.8.7 survival with a LAN connection to one other player. Both players affected.

Confirmed in 1.8.7 with a player connected by LAN to my game, his enchanted picks break and then reappear when he tries to replace it in hotbar. (The "replacement" falls on the ground and the "broken" pick reappears in hotbar.) He can do this several times before it truly breaks.

1.8.7 on a LAN connection with one other player. I (host) do not have the bug but my other player (connected player) sees upper-half Peonies everywhere he goes. He sees them in my area and his (~1000 blocks apart). Breaking them does not drop anything; they re-appear upon reloading the chunk. Where he sees these floating Peonies, I see nothing of note.

1.8.7 peaceful survival mode on a LAN connection with one other player. Tamed/saddled horse despawned after going through a nether portal and returning to area (about 5 minutes later). All untamed horses were still present, but saddled horse gone. (No name tag, no lead, not confined.)