I migrated my Lightroom 5 from a PC to my new Mac. My catalog still has a C: drive and other external hard drives I was using with the windows Computer. I am now trying to Sync the folder with all of my folders on the Mac's external hard drive (different from the one used on the PC) and I am affraid if I uncheck do not import duplicates, I am missing many images because they exist on a different drive of the catalog. Can someone tell me how to remove these old drives from my catalog?
When you reconnect your Lightroom catalog to the photos on your Mac, you need to follow these instructions: Adobe Lightroom - Find moved or missing files and folders
You want to reconnect the top-level folders where your photos were stored as shown in Figure 4.
There is no importing of photos involved, so there is no need to check or uncheck "do not import duplicates"