As a user I want to run multiple sprints concurrently so that multiple teams can work from a single backlog

With a single team working through a backlog, it makes perfect sense to have a single RapidBoard restricted to one active sprint. We operate with two teams running off a single backlog and can't see how to do so effectively from the RapidBoard.

Ideally we'd all use the same RapidBoard and set the "active sprint" limit to 2 so that both teams can have a sprint active.

Instead we figured that each team would create a separate RapidBoard pointing at the same backlog but now it seems that the 2nd team still sees the 1st team's open sprint and is blocked from creating a new one. How are we supposed to operate two teams from a single backlog?

If we're going to be forced down the route of maintaining per-team backlogs then we're going to need some better tools for managing multiple backlogs and easily moving issues between them.

(All of this works quite easily with per-team sub-versions in the classic boards btw)