If you have photos inside and outside of the Apple iPhoto library; and both types of photos are being managed by Fotobounce; then if you import a photo from outside iPhoto into the iPhoto library you will end up with duplicate photos in Fotobounce. The reason for this is that iPhoto modifies the metadata so that Fotobounce sees the original outside iPhoto and the copied photo inside the iPhoto library as a new photo.
The workaround is to mark one of the photos hidden in Fotobounce.
