If both your monitors are the same resolution you can actually already do it.
Instead of maximizing Construct 2, stretch it manually over your two monitors.
Then take the event sheet you want to have on the second monitor and drag/drop it to the right of the layout view, it will create a separation in the UI.
Move that separation to fit the separation of your monitors and you can use C2 on two monitors at once, having layouts/event sheets separated and yet displaying at the same time.