In order to use the same key on multiple instances of Blockland at the same time, they must be on the same modem (LAN network).
I do not mean the same model, or same provider, I mean same physical modem.
Otherwise you'll get authentication errors and Badspot will yell at you.
Do not try to get around this. I wont be surprised if certain people got banned in this topic.
I have used my key on several ip's, not one warning or any response. You're allowed to use Blockland anywhere.
How far were the different locations?
I recall him saying at one point that he'll only do anything if you somehow traveled thousands of miles in only a few minutes.