When we update to 5.2.5, there will be a fail-safe added to help prevent inventory wipes. The server will prevent you from logging in if you are already logged in. It will not try to disconnect your other session, you will have to wait until the server figures it out for itself. This may take up to 2 minutes.
So why would you already be logged in? Sometimes if you crash or disconnect improperly, the server isn't informed that you closed your connection and still thinks you're logged in. Due to a glitch in Bukkit we cannot properly save your inventory when you log back in because Bukkit reports the WRONG player. Hopefully they will fix it soon - but in the mean time if you are rejected from logging in - don't get mad! Just think that your inventory is being spared and will not wipe. Yay!
