My Aperture library has only referenced files, no images were stored in the library. After importing the Aperture library with Lightroom 6 (Mac version) I ended up with a large number of date-specific folders (YYYY-MM-DD format) under the LightroomMasters folder.
If I use the "Show in Finder" command in Lightroom, Finder shows a file with some number appended to the end of the actual filename, for example IMG_9218_119841.jpg and the same folder also has the file without the extra number (IMG_9218.jpg).
Lightroom seems to have correctly imported the referenced images in their original location but why are these extra images copied to the LightroomMasters folder?
Common question. See some of my other posts about using referenced masters before migration. Only way to maintain a "folder" structure you desire. "Collections" should mirror your Aperture layout, but that's not what most people desire.