Pre-sale CD Keys

I realize this might seem dumb, but I haven't been able to find an answer anywhere.

If you get a pre-order/pre-sale CD with the CD Key, can you add that to your account to get the additional benefits even though you already have the campaign?

For example: If you already have Nightfall installed, could you add a Nightfall pre-sale CD-Key to get the bonus items?

Yes, you can. It worked for me with the Prophecies pre-order that I added after Factions was released.

Cool beans! Thanks for the info.