I tried to update an existing form using XLSForm Online v.2.x. I followed all of the instructions in the documentation (including maintaining the filename of the .xlxs file). When I tried to upload to Aggregate v.2.0.3 I got the following error: ''Form Already Exists for this Namespace/Id attribute'. I looked at the XML for the old form and the new form and realized that the filename was missing from the new form, but it appeared 415 times in the old form. I fixed the problem by using the Previous Version of XLSForm online.
I am posting here as in case others have the same issue and to find out if this is a bug or a deliberate change. (The filename thing was quite annoying in the previous version).