I just upgraded a 2008 Mac to Snow Leopard (10.6.3) and then to Yosemite (10.10). After the 10.10 upgrade I ran iPhoto Library Upgrader. I now have two 78GB files/databases, 1) "iPhoto Library.migratedphotolibrary" and 2) "Photos Library 2" The 2nd I assume is the one I will work from going forward. I assume the first is is what remains from the prior photo app and related file format. My question is can I delete the first file/database listed above? And if I can, should I delete it or should I keep it for some type of recovery purpose?