Tim, I'm not sure what exactly you mean by "common in both". We do have an app on our marketplace for a data loader which can be used to import data as well as updating data, it sounds like that will accomplish what you are looking for. The link to the app is: http://www.clarizen.com/appsmarketplace/Data-Loader.html. Please take a look at the documentation there, as well as the documentation available on the tool once installed. There are full explanations as to how to structure the CSV file for import / update.