CatDV can deal with clip records that come from a variety of sources, for example importing a media file or batch log, and you might do things like export a clip to another application then re-import it. The question then arises of when are two clips the “same” or not? (See also: Summary mode)

A number of different fields in CatDV can be used to identify a clip:

Clip ID
This is a new general purpose clip reference field. You can choose to have clip IDs assigned automatically (it will get a random number calculated from the clip name and the time the clip was first imported) or assign them manually if you have an existing library system or want to refer to external catalog of assets. You don’t have to use this field, you can leave it blank and you can have multiple clips with the same clip reference if that makes sense in your system.
File Hash
Whenever you import a file into CatDV a checksum is calculated based on the file contents. Although not guaranteed to be unique, it is unlikely that two files will have the same file hash unless they have the same contents. If a file has been renamed or moved, or there are two copies in different places, the file hash indicates they are really the same. (If you open an older catalog which doesn’t include the file hash you can calculate it using the Tools > Re-Analyse Media command.)
Media Signature
This is always calculated automatically and is based on the media that the clip refers to. In the case of movies with a timecode track or clips that refer to a tape it will be based on the tape name and timecode, in the case of other media files it will be based on the file name and file length. In most cases, if you have two clips that refer to the same piece of media they will have the media signature, even if the clips themselves are named differently or the media file has been moved or is offline.
Remote Object ID
Finally, when a clip is saved to the CatDV server it is assigned a unique numeric id in the database. This number is not normally displayed on the client application but may appear if you use the Live HTML Publisher, for example.

Find Duplicate Clips

The Tools > Find Similar command will find duplicate clips which are similar to the selected clips based on a particular attribute. It will either search all the open catalogs in memory or compare the current catalog with the CatDV server. For example, you might compare on File Hash or Media Signature to see if anyone has already imported a particular media file.