please allow for file copy overwrite according to modification date, so that if chosen only new files will be overwritten instead of all of the files or none. Reproducible: Always
Thanks for the report! This issue (which is not Dolphin-specific, by the way, because you can also use FolderView and quite a few other KDE applications which use the KIO framework to copy files) has been reported already. *** This bug has been marked as a duplicate of bug 94670 ***