If I used two clubs to Sunder a shield do I roll two cmb checks with no two-weapon fighting penalty ?
When you attempt to perform a combat maneuver, make an attack roll and add your CMB in place of your normal attack bonus. Add any bonuses you currently have on attack rolls due to spells, feats, and other effects.
CMB check is an attack roll, all you modifiers such as from weapon focus, enhancement bonuses and 2 weapon fighting apply.
(assuming you are using 2 weapon fighting to gain an extra attack rather than using iterative attacks with 2 different weapons naturally)
Without the two weapon fighting feat