Could “appear” be clarified please? Does it refer to a “dlist” filename which has a readable date put in the name (e.g.
duplicati-20190713T235905Z.dlist.zip.aes), or does it refer to a file modification date?
Do dates and names change when the files reappear? Duplicati backup would use new names, and likely new file modification dates. Seeing old files with old names and old dates may be something else, pCloud Sync could be syncing an old backup (though I thought sync is two-way, so why aren’t originals deleted?).
How can I backup my content from other platforms to pCloud? is a way one-way old file copy could occur.
Have to agree with that, but to find what the something is might need a look at the details of what’s written. Getting more ambitious than a better check of external file properties such as names and dates could be:
Restoring files if your Duplicati installation is lost may be a way to take advantage of the Duplicati reinstall to at least see what’s in the troublesome files. Be sure not to go too far. A direct restore (maybe even only the initial steps of seeing what versions you have and what files they contain) is fine, but don’t recreate the backup job if there might be another on another computer using the same destination. They’ll collide there.