That is you were trying to add two fields using the same property, right? E.g., two separate fields using
dc:title or something like that? This is indeed a necessary constraint of the data model; instead we are planning support multiple values for the same field in the future. This means that it will be possible to add, e.g., multiple
dc:title values to the same field (as opposed to multiple fields of the same property).
Furthermore, Tropy manages metadata at three levels (item, photo, and selection); in theory it is possible to customize the templates at each level. So you could, for example, record the original archival data at the item level and the website’s information at the photo level (since the photo is just one concrete photo or the original item after all). I think this is close to what you are suggesting and actually how we envision templates to work (i.e., you can define an item template and its corresponding photo template), but we have not enabled this in the UI, because we were worried the ensuing complexity might overwhelm users (the photo and selection templates are locked at the moment). I’ll make a note of your request; I think there is a good chance that we will add custom layered templates – we just need to make sure the template editor is easy to use (in its current form it’s not yet easy enough!).