Backup duplicates photos and videos from iphone8

I have backed up my photos and videos from iphone8. I have 9000+ files on my iphone.

After backing up 1000+ files to my new 200GB wireless sandisk stick, the stick baterry went low.

I had to recharge and resume the backup.

When backup was resumed, it started from the first file and created a filename subscript of _1 and will put _2 for the suceeeding tries for the same file.

I have noticed viewing the files from Windows Explorer, the modified time of the file is the current time when the files are written  or backed up to wireless stick. 

This is not good as it will create more duplicated files everytime you run the backup. This is the same as running a full backup everytime you run the backup. 

I am expecting running an incremental backup everytime you run the backup which skip the same filename.

I have installed Connect Drive version 3.2.3 (1188) Firmware 4.1.0 (2050).

Is there a fix or settings to avoid duplicating files ?

the backup is an incremental backup. There may have been something go wrong with the backup when the battery went low so next time it started a new one. 

If you have not deleted the pictures from your phone I would try deleting the backup on the wireless stick using a computer. Then restart the backup. you can plug the wireless stick into a USB AC charger (Like an iphone AC charger) and this will prevent the battery from dying or getting low during the backup. Once it has finished take a few more pictures then reopen the app and it should only backup the new pictures. 

Same thing happened to me, my stick battery was 100% charged. I had about 3000 videos and pictures on my iPhone 6. I had to use Duplicate Cleaner sofware to clean up this mess. It just sounds like the Sandisk Backup has hard time to deal with too many files. So many times I see the same files with suffix _1 then _2 then _3… - login IP Login Address.