Many-to-Many: Which Dimension is Used?

In SSAS, it is possible for a M2M to have 2 paths. The first one is through Dim1 and second one is through Dim2. In this case, which path will be used by M2M? I've come across this question about 2 years ago, and have been delaying finding the answer until now. So here it is.

Ah before I start, 2 things. 1) This post is related this [link] post I wrote 2 days ago: Many to Many Is Not Always Right. 2) Thank you to Robert [last name] for bringing this up. I came across it for the first time 2 years ago, and I've always wanted to find out.