In 2011 I moved over to Aperture from iPhoto, and, although I can't remember how, I had access to the old iPhoto pictures via a folder in my managed Aperture Library.

Some time last year I eventually got around to merging the two libraries and now have one managed Aperture Library of 463GB containing 49,059 items on my iMac.

I recently discovered in my Pictures folder that I still have an iPhoto Library of some 47.86GB. I also found out that I can open this library even though Aperture is open and it says there are 32,791 items in it. It appears to be my iPhoto library up to the point I stopped using it in October 2011, although I'm pretty sure that it was larger than 47GB before I merged it with Aperture.

Why would I still have this Library in the pictures folder and would it be safe to trash it?