Impossible to delete images

Hello,

A freelance I hired did a mistake with WPML.
He duplicated all my content 2 times.
I need to delete this duplicate content.
But when I delete an image, it is deleted in the media library but not on the FTP like you can see on this video : https://www.loom.com/share/77a2b26e8af74df79f291448675af095

For example, I have an image named Telephone-Xiaomi-Redmi-9AT-Bleu-1.jpg (the “-1” here is because I rank my image to know in which order to put them).
I have 4 times this image and I don’t which one is attached to the product so I delete them 4 and I upload a new one to replace it.

But even if I deleted the 4 images and cleared the cache, when I add the new image, its name is now Telephone-Xiaomi-Redmi-9AT-Bleu-1-1.jpg. The second “-1” is here because the file are not deleted in the FTP.

So do you know why, deleting on WordPress doesn’t delete the files on the FTP ?

What I already tried :
– deactivate all the plugins except WP Rocket to be able to clear the cache, WP staging Pro to work on a staging site and Woocommerce
– I also tried with WP Rocket deactivated
– I cleared all the transients
– I do not have Jetpack

Thanks a lot for your help