[Nick_K]

You don't need two lucky pendants to have two separate sources of luck. The lucky pendant and shield can be used together. They're different items so you wouldn't even need sone multiple slot trick....

But as Endoperez says, luck is a unit flag and is either on or off. You can no more have 'double luck' than you can have 'double flight'.

The most obvious effect to me of this situation where duplicate items don't take effect is with bags of wine. IIRC having two on one commander only gives the effect of one. If you have two different items that give the supply bonus both work though.