Hide previously imported images

I have moved from Aperture to C1, and gone from a managed to a referenced library. The one little feature of Aperture that I miss is the ability to check a box and not see previously imported files on my SD or Compact Disk. I can get around it by sorting by date, newest first, but it was a convenience. As I recall, Aperture knew not to spend the time imaging the whole disk.
While I'm making the transition, it would also be nice if that feature applied when importing the files from my managed library. That way I could move the managed library to a reorganized referenced library, by importing files rather than the whole library.
While I was a real fan of Aperture, I frankly like C1 better, probably because of the excellent webinars. There has never been a program that has been so supportive. Thank you.