Regarding Successive Locks

I apologize if this has been covered, but I did a search for Lock and I think every thread ever written on any topic came back in the results.

Anyway, my question is that if character A successfully Locks character B, and then attempts a second Lock, do the dice from his second Lock stack with his dice from his first lock (say 1 was 3D and 2 was 2D, would the total Lock be 5D?) or can you only try to improve the lock (which in this case, would have actually worsened it from 3D to 2D)?

You increase the Lock. See Increase The Pressure on p448.