Understanding import duplicates

Hi everyone,

short off-topic block:

I made the switch from lightroom a few months ago, and I’m blown away by how awesome darktable is!
It has honestly been a great source of joy for me to work on understanding how the software and all the modules work. I’m lurking on this forum a lot, and watch a lot of videos by the many great content creators!

I wanted to use my first post on here also to say a big thank you to all collaborators on this great project and to all content creators who helped a lot making all this accessible for me!

Now about my issue:

(This is on the nightly windows build of DT, 4.5.0+1377~gca67684661)

I use the following naming scheme for importing my photos:
base directory: $(HOME)/photos/general
sub-directory: $(EXIF_YEAR)/$(EXIF_YEAR)-$(EXIF_MONTH)-$(EXIF_DAY)

I usually copy&import straight from my SD card, but I also did an initial copy&import from my local raw folder when i made the switch from lightroom.

Now today I took some photos using an SD card which already hat some photos on it, that were already previously imported (from disk, during my initial copy&import).

After my photo session the SD card had the following contents:
DSC_1871.NEF to DSC_2081.NEF (207 old photos, with some gaps in numbering)
DSC_6330.NEF to DSC_6378.NEF (new photos)

I copied & imported and had [x] select only new pictures selected. However all pictures were selected.
This created duplicates for the old photos, they got copied into the correct folders but were named
20231204_0001.NEF - 20231204_0207.NEF.

So trying to understand how this behaves I have the following questions:

  1. Where does this naming scheme come from? Is this a fallback as to not overwrite any images?
  2. Why were the images not detected as duplicates? Does it make a difference that I previously imported them from disk instead of straight from SD card?

EDIT: Regarding question 2: At one point I made a change to the timezone or time in my camera, could this have affected the hash values of the images?

Thank you for reading my post!


It could be that also you have this option…


To be honest I would have to go and try now to see if it will import a second time as duplicates without that selected… I didn’t think so… but your time change may make it appear as a new variant or duplicate…

1 Like

Thanks for your reply Todd,

I had that option checked, but it still selected all files on my SD card.

I did a MD-5 check, and the raws from the original import and the re-import are identical. However, curiously my windows explorer shows a different last modified time (differing by 40 minutes, which I think is what I changed on my camera.)

So maybe last modified time factors into duplicate detection too?

Normally I think you just see them checked if they have been imported and any new ones show as not yet checked…

I manually import all my photo’s and so the importing into DT is really just DT creating a database entry for the file location….