LR CC won't stop importing duplicates

[Stidik]

I'm new to LR CC, converting over from Aperture. I'm using a MBP with 2 external HDs while on vacation in Europe. Shooting 100 to 250 images per day. Importing Copy as DNG, to external HD, LR Photos. Importing  from a SD card. Also backing up to 2nd external HD, Backup Photos, at the same time. "Do not import suspected duplicates" is checked!!  But each day hundreds of duplicates are imported anyway. Also the standard "shift" command does not work. So I can not unclick all the images,  then select the first new image, then "shift" select the last new image. I would greatly appreciate someones help.  Thanks!
I am so so sad to learn of Michael's passing, he leaves a tremendous legacy.

[stingray]

I import my images to Lr, take a backup of my images to an external drive, put the card back in my camera and format the card.   

For me,there is nothing worse than having duplicate images in my catelog, so I do not depend on Lr to manage this for me.

More importantly, using the same card for multiple shooting sessions and importing to Lr between sessions, leaving your images on the card is a high risk strategy.

I do not know what rules Adobe applies to determine what is a duplicate image and to-date have not seen anything published, so until I have clarity on this I would not depend on this Lr feature.

 

[RikkFlohr]

Do you rename during import? If so, that is the issue.

Do not export duplicates works well if you do not rename. It doesn't work at all if you do rename.

[fdisilvestro]

LR should identify the "Suspected" duplicates even if you rename when importing. There is a field in the database "importHash" that includes the original filename and it looks that it is the field used for comparing duplicates or "suspected duplicates"

The following is the "supposed" Lightroom criteria for duplicates:

Duplicates: Same Path, Filename (original), size and timestamp
Suspected duplicates: Same Filename (original), size and timestamp

So the difference between duplicates and suspected duplicates should be the path (drive/folders)

Also the standard "shift" command does not work. So I can not unclick all the images,  then select the first new image, then "shift" select the last new image.

In the import dialog, uncheck all, then click on the first image border (the grey area), then shift-click on the last desired image (again in the grey area) now tick the box on the upper left, you should have the desired  images selected. You can also ctrl-click or cmd-click in the grey area to select non-contiguous images