I heard a rumor that there is a new /duel command in testing!
It is very exciting!
This means that players can practice PVP with friends without loosing inventory or dying/re-spawning.
The format is like the /g friends command in the sense that it only works when both players agree.
I think the command is
/end duel - but this might also time out after a while
Feel free to test this and post your thoughts here.