We have multiple systems that contain clients. We're working on a new system to combine these clients into a single system. Our current layout is very much like a product comparison page.
The problem now is that we're incrementally adding in existing systems one at a time. The last count was 7 different systems. It also turns out that a client can be in some systems more than once. In the end, only one instance of a client will exist in the Combined System. We obviously can't just keep tacking on columns for each time a client appears in any system. Our first idea was a dropdown in the column header with each system being a choice:
If we went with this, it's the least amount of work for us to change the existing page but I'm not sure that it properly caters to the users of the site. I feel there's something wrong with putting them in a table because we expect many of the values to match. A client only has one Date of Birth or SSN as well as other fields I'm not showing. I think the norm should be to only show redundant information one time and the exception is to show where two different systems differ but I don't have a clear idea for how the UI should actually present that in a clear, reliable way.