Log off account (?) glitch

(Was on creative on flat world) I logged off of a world and a while later logged back on and build something. I cleared my inventory and built it. I exited the world to check another world for reference of the thing, and upon logging back on to original world I was where I logged off, from the first time. Also my inventory was the same as when I logged off then. What I build a minute ago was still there though. Note that this has happened twice already. 

Steps to reproduce

1. build something on a flat world

2. log off and wait a few hours-days

3. log back on to world 1 and clear inventory, then build something else

4. Save and go to a world 2 and stay there for a few minutes

5. return to world 1

Expected results: you will be where you logged of before going to world 2 with your inventory from then

Observed results: you will be where you were a few hours-days ago with inventory form that time, your build will still be there

Note this is probably not a guarantee every time and you may have to try a few times to see this

UPDATE: It acts like 2 separate accounts with different inventories and log-off locations