BootMii handling of page/cluster "spare data"

Does BootMii fix incorrect ECC/HMAC data?

ie. I modify the data for a cluster in a nand dump, but don't change the "spare data" at the end of each page. Can I "restore" this dump, or do I need to create the proper ECC/HMAC data?

I think you need to create the data. BootMii probably doesn't autofix this data because that could allow the writing of corrupt dumps.