When you duplicate a Family Type of a Revit Family the parameter "Key Attribute” will be cleared. This will ensure that it will not be duplicate for the value that is meant to be unique for the dRofus syncing function.
Example:
"Data: drofus_article_id" is the Revit parameter used as the "Key Attribute for comparing" in the Default Configuration:
2. Type 1" is linked to a dRofus Item (using "drofus_article_id" = 6049)
3. When duplicating "Type 1" to a new Family Type "Type 2" the new type will have "drofus_article_id" = set to <blank> as shown:
This will ensure that no two or more Family Types (created by the "Duplicate" command) will have the same value as the "Key Attribute used for comparing", meaning the link between the (originally linked) Family Type and the corresponding dRofus Item will never be lost.