I noticed that too as I started the d/l the weekend. I knew that the CHD set was bigger due to the LD games they constantly add, but I don't know why it is also with the normal ROM set, I guess you have to look in their forums.

I wanted to join mine, and as it really only joint at 43%, I deleted it and started an whole new clean set, didn't want things to perhaps get too messy, and as it's a free torrent, it doesn't really matter. From time to time I just want to make a fresh download to keep it proper.

The Extras are also now over 13GB, probably it's the core & alternatives merged?