There are still two preview groups, the -Preview 1.7- one and the Second Life Preview one.
I think the old one with the obsolete version number in its name needs to be eliminated.
What is the purpose of keeping the old group around?
Vektor could send invitations to all the group members for that group to join the Second Life Preview group, make a group notice explaining that the old group will be deleted on some specified date in the near future, and on that date either dissolve the group using Linden magic or expel everyone and then leave the group.
If there is a function to having the old group around - what is it?
If there is no function to having the old group around - at least take the time to make it not open join so people don't join it by mistake and miss out on the few messages that occur in the proper preview group.
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Yes, as Torley pointed out in reply, I am in both preview groups now - thanks to the increase in max number of groups I was able to join both groups. If I can find more groups with worthwhile chat going on I will get grouped up again and would prefer to have just one group slot used for previews.