Photo and preview from External Drive seen twice in the media

all the photo that are stored in the external drive are seen twice in the photo app of nextcloud as well as nc-photo in android…
For instance, a photo captured through the phone is then seen twice by the nc-photo or nextcloud app:

  • The 1° photo in the folder “2023/09”
  • The 2° photo, actually the preview of the 1° photo, in the folder “2023/09/.thumb”

Can I hide the thumb photos? May i did any mistake in the previews generator config?
(I have NextcloudPi, v. 27)
Thank you!

The errore Is still present. Anyone has any suggestions?

I discovered that was my NAS Zyxel 326 whiteout my indications that was creating the thumbnails.