Class Action?, page-16

I signed up with the Maurice Blackburn Class Action (the Basil CA) early last year after having to sell and losing over 60% of my investment. Received an email (with attached forms) from MB explaining the two class actions in the federal court and how theirs is now a "closed" class action whilst the Slater and Gordon one (the McKay CA) is an "Open" class action. Then went on about options to opt out of either if I wanted too.
Then got another email from the S&G class action saying much the same thing and a letter today. Its hard to know what to do here.
I thought that the court had decided that as the two CA's are very much identical, then only one should proceed and the outcome of it would determine both. Have I got this wrong? My gut feeling is that I would rather be with MB than S&G but I have no idea of the ramifications of a CA being "Open" or "Closed". Would I be better of in one or the other or would the benefits be the same. Have never participated in a CA and am hearing different opinions on whether they are worth anything to the mug punters