I accidentally started a second instance of the server on wind 10 (one little DOS windows in the background eluded me).

Since it had the same settings file, the port and world name were identical.

It ran happily and I logged in and payed for a while.. only to discover that existing and logging back in again reset my game to the same point at which I had logged in.

(so no progress made but)

Suggestion: warn or prevent a second instance listening on the same port with the same name as an existing instance.

It was a bit of a cheat for me as I found diamonds the first time round. Second time I logged in (after stopping the second instance) I could go directly to the diamonds