I believe 'may not modify' just means you've to upload it in its original status exactly as the time you downloaded it. So, after you played around with it you still have to replace it with the original one before uploading.
It's very likely that different candidates may get different versions of db schema or records so Sun have to check against it. Or Sun has written certain
testing routines to assess your assignment and that have to be applied on the original record to obtain expected results. If you add some junk records, it's likely their testing would fail! - No, that means you'll fail!
If a database cannot be modified and updated, what is its practical purpose??