However the two files are quite different in content (both are small, but have distinct different sizes too). These different contents are shown both in Finder’s quick view of th files in the iCloud folder and when I open the files in DEVONthink.
Despite this, when I search for words occurring in the first file the file is not shown in the result list at all, but when I search for words in the second file, both files are listed although the word in fact only occurs in the second file!
Why is this happening and how can I tell DEVONthink to update its internal information, so that it sees the two files for searching and for its duplicate detection as different as they are. (I have done File → Update Indexed Items on the enclosing folder.)
Firstly, you can enable Settings > General > General > Stricter recognition of duplicates to have DEVONthink consider file type, file size, and a content hash in duplicate detection.
Secondly, you seem to be reporting abnormal behavior or your database isn’t healthy. Hold the Option key and choose Help > Report bug to start a support ticket. Attach the two documents for us to inspect.
I sent the Debug info to DEVONthink and they quickly checked it. Jim recommended a Database Rebuild. - And this did the trick! Now the two files don’t show up as dupes anymore even with “Stricter Recognition” _un_checked. Plus the searches work as expected!