I can't think of any reason why the suburb/state/country would be any different to the existing boundaries. 

Even if they were different, there is no way to tag that this is the case and when people do QC checks they'll get flagged and then changed to match anyway. 

The other thing is that iD seems to prepopulate the fields anyway, so in effect it's just copying information that's already been mapped. I had a bit of a play around with it here and it suggested that the suburb name was 2085! So it doesn't even necessarily copy in the correct information.

This one I only looked at because it was flagged by Osmose as having opening hours errors. When I check the other tagging it is just easier and quicker to delete the duplicate information than it is to go off and check it.