we were playing lan multiplayer like we do often. then i got lag so i logged out to log back in because that usually helps against lag. when i tried to log back in it timed out, but it does that more often so i tried again and then it worked. HOWEVER, when i joined multiple weird things were going on:
1: i spawned in at the spawnpoint of the world instead of where i logged of
2: my skin didn't render, i was just alex. i did however have the items i had when logging of.
3: a second alex spawned with my player name (MinerBat) it reacted to the same input as the one i was (so if i pressed W we both moved forward, S both backwards etc.) with a little bit of delay.
4: the other players saw 2 alexes moving both with MinerBat as their name
5: the tab screen showed 2 MinerBats with alex face
6: at the location i logged out in at the start there was a 3rd player.
7: the 3rd player had my skin but only the bottom layer was rendered (you can have 2 skin layers). but had no name above his head and didnt show in tab menu. (i should have looked if he had a hitbox but i didn't think about checking that at the time)
8: it said MinerBat joined the game twice in chat

after a few minutes i relogged again trying to fix it. this is what happened then:
1: i went back to my old logout location and got my skin back normally
2: one of the alexes disappeared (presumably the one i was controlling directly but is no way to know for certain) but the other one stayed in the world and on the tab screen
3: this alex didnt do anything anymore except for floating
4: using /tp MinerBat 0 100 0 affected the alex but not myself
5: using /gamemode survival MinerBat put me in survival normally, the alex was still floating in the air but could take damage
6: restarting the lan world entirely (having the host account log off and on and creating a new lan world) made everything normal again

Steps to Reproduce:
sorry, i have no clue. we play lan quite often but this has never happened and there wasnt anything that we did that we don't do usually

i understand that you would want a log file. i will ask it to my little brother as soon as i get the change (the lan world was on his computer)