Does WinRAR detect duplicate files

1. Open regedit

2. Go to HKEY_CLASSES_ROOT\WinRAR\shell\open\command

3. Change the (Default) value from "C:\Program Files\WinRAR\WinRAR.exe" "%1"
   to "C:\Program Files\WinRAR\WinRAR.exe" x "%1"

4. If you have ZIP files associated with WinRAR too, change the corresponding value under
   HKEY_CLASSES_ROOT\WinRAR.ZIP\shell\open\command too.

(Obviously for 32-bit WinRAR the path will be different.)

This however will probably not create a sub-directory named after the archive in the current directory while extracting. (At least it doesn't for me given my WinRAR settings.) For that you'll have to change the (Default) value(s) mentioned above to something like "C:\Extract.bat" "%1", then create the batch file with the following content (just a single line):

"C:\Program Files\WinRAR\WinRAR.exe" x %1 "%~n1\"

This should do what you want, and as a bonus you can now right-click and "Open" multiple archives (or select them and press Enter) and they will all be automatically extracted to individual sub-directories by the batch file.

Note: The Extract to <archive name\> context menu entry is generated dynamically by the shell extension based on the archive's name, so no key by that name exists in the registry. For a static key it would be simple to just set it as the default action instead of Open, but this is not possible here due to the dynamic nature of the option.

use 7-zip to extract them directly (don't use a file joiner)
Unlike Winrar , 7-zip can handle those .001 type files.If one of the archive is corrupt it will surely mention the part ( " crc failed in part x " ) but this will occur only if the data is damaged during downloading .
If this is not the case you can only solve this with the help of a recovery record. Simplest way is ask the person who uploaded the files to give you each file's checksumthen compare each of your own file's checksum with it the file with a different checksum is corrupted.