Double Dip?
 

My wife is Silver and signed up for the Unexpected Bonus promotion. Last week she had another promotion arrive called Welcome Back which will give her a free 1-4 category night for each two stays up to two free nights. So if she stays two nights will she get one 1-5 night and one 1-4 night?

In general, Marriott has seemed to run each promo completely independent of other promos. The result is that usually you can earn nights/stays/whatever toward all the promos you are signed up for at the same time. So you can most likely get both certs for your two night stays.

Normally, I would suggest calling and asking Marriott just to verify (and it couldn't hurt to do that), but I'm not sure they would really know the answer. They might tell you yes or no, but I'd be worried that they were just guessing or making it up.

I can confirm promos are independent of each other. Just logged 2 stays and it appear that I have 2 nights free on the books.

I should have checked back in on this thread and reported she too got two free nights for two stays.