hmmmm........ earlier today I marked a WL book received.  Just now I went to WL to view it and discovered 3 other versions of the same book still on my WL, but no longer highlighted in pink as they were when the book was 'en route' to me.  I thought the highlighting meant the books were linked and they would disappear once I marked the transaction completed satisfactorily.  

There is a check box that asks if you want alternate versions removed from your WL when you mark a book received.  I cannot remember if that box is checked by default or if you have to remember to check it.

Also - if the books aren't connected via the system they won't be removed. You have to do it manually.

caviglia - wouldn't the fact that they were pink while the book was in transit show that they were connected via the system?

You can't trust that. I hardly ever see the check box option when marking WL books received.  I've just learned to routinely go through and check.

They were probably never highlighted in pink (i.e, are you certain they all were - there could be versions both linked and not linked?). As Mary said above, mostly you just have to manually remove them.