Can two people play on the same minecraft account at the same time?

Not in the same world, on a server in multiplayer or anything.
My boyfriend had me create a world of my own on his account and when I got home
I downloaded a cracked version, played it and today, I lost a huge amount of things I did in the game,
I stored a bunch of things in chests and they all disappeared.

So! What I'm asking is, Can he play his world on his computer, and then I log into his account on myyy computer and play my world? At the same time he's on his world?

Yes. You can do this.

Yes you can. My friend plays minecraft on my account and nothing happens.(only the skin changes if you change it)