Indeed i've been thinking what it could possibly be, and didn't find anything on how to solve it...
The problem is that the P2770HD is 6mm higher then the regular p2770, wich is pretty weird imo for 2 products of the same series...
Edit: now that i'm thinking of it, i might try and switch the stands and see witch one is higher then and try to get 2 identical stands so they would level out...