How good is the Photo Downloader at detecting duplicates?

Question

I have only tested the Photo Downloader (with version 1.2) once, and I got a couple of hundred duplicates on my disc. I had images on the card that I had downloaded before using other software, but images that was already in the LR library.
So, I'm not sure that I dare to use the Downloader again as long as my card has still old photos on it.
What are other users experience with this program?
Other programs I have used for downloading from the card uses the Archive-attribute so it can know for sure if a picture has been downloaded or not, so why does not LR do that? I'm not sure if Mac has the same file attribute, or if all camera manufactures uses it, but if they do, then it could be a good idea for LR to do the same.

Answer 1

I suspect no better than it is at detecting duplicates by regular import. Here is a quote from an earlier post of mine on the subject of LR's inconsistency in detecting duplicates. That was with 1.2. I have not fron a formal test on 1.3 yet, but informally it seems to catch more than 1.2--but that is just an impression. For sure, it is not getting them all by any means. That I know from importing in 1.3 and seeing identical files in the import. By identical I mean everything, name, ext, size, dates, crc,everthing--abjectly identical. I will run some tests when I get an hour or two. By the way does anyone know for sure just what attribues of an image LR uses to determine identicality. Given the use of the word 'suspected' duplicates, I suspect that it isn't a very rigorous test. Something is either a duplicate or not!
Here is what I posted earlier based on testing:
"I have recently undertaken to run a serious test of LR 1.2--as I did with previous versions-- to see if it was at the stage of development where it would improve my workflow over my present applications. Most everything is much better than before, but I have discovered a killer bug.
I work in a group of four other photographers. We are constantly mixing and matching images from our various DBs/shots for client presentations, frequently mixing shots already in a DB with some that are recent and not yet DBed In the end, of course, we want one DB that incorporates all our collective images. This arrangement lends itself to imports that often will contain duplicates of given, uniquely identified, images.
I discovered that even with the box checked to not import duplicates, that LR is hopelessly inconsistent in stopping the import of absolutely identical files with absolutely identical names, extensions, metadata, etc.
As a test, I imported a set of 50 images--various formats, etc--all of which were in LR already. I ran the test three times. The first test resulted in LR identifying 3 dups, the second test 17 dups, and the third 13 dups. I also tried this test using images that were in two separate LR catalogues--identical in every respect. LR did not identify even one duplicate image of the fifty in this case.
Is this a known bug? Anyone have any suggestions? TIA "