A duplicate attribute key has been found during processing (revisited)

This blog post is my 100th post here and I'd like to say a big thanks to all the readers and supporters of this blog. Reason enough to concentrate on a very popular topic from my past blog posts.

Back in 2009 I wrote about the typical cases for the duplicate attribute key error in SSAS. From the response I got to this post this is still a very common error message causing confusion. Reason enough to revisit this topic and complement my last post with three new variations. Thanks for all the comments, as two of the cases are taken directly from the comments on my previous post.