Balance conversion to metadata RAID1, data RAID1 leaves some metadata as DUP

[Pete <pete@xxxxxxxxxxxxxxx>]

I recently recovered created a fresh filesystem on one disk and
recovered from backups with data as SINGLE and metadata as DUP.  I added
a second disk yesterday and ran a balance with -dconvert=raid1
-mconvert=raid1.  I did reboot during the process for a couple of
reasons, putting the sides on the PC case, putting it back under the
desk and I updated the kernel from 5.3.9 to 5.2.13 at some point during
this process. Balance resumed as one would expect.  Balance has now
completed:

root@phoenix:~# btrfs balance status /home_data
No balance found on '/home_data'

However, some metadata remains as DUP which does not seem right:

root@phoenix:~# btrfs fi usage  /home_data/
Overall:
    Device size:                  10.92TiB
    Device allocated:              4.69TiB
    Device unallocated:            6.23TiB
    Device missing:                  0.00B
    Used:                          4.61TiB
    Free (estimated):              3.15TiB      (min: 3.15TiB)
    Data ratio:                       2.00
    Metadata ratio:                   2.00
    Global reserve:              512.00MiB      (used: 0.00B)

Data,RAID1: Size:2.34TiB, Used:2.30TiB
   /dev/mapper/data_disk_ESFH      2.34TiB
   /dev/mapper/data_disk_EVPC      2.34TiB

Metadata,RAID1: Size:7.00GiB, Used:4.48GiB
   /dev/mapper/data_disk_ESFH      7.00GiB
   /dev/mapper/data_disk_EVPC      7.00GiB

Metadata,DUP: Size:1.00GiB, Used:257.22MiB
   /dev/mapper/data_disk_ESFH      2.00GiB

System,RAID1: Size:32.00MiB, Used:368.00KiB
   /dev/mapper/data_disk_ESFH     32.00MiB
   /dev/mapper/data_disk_EVPC     32.00MiB

Unallocated:
   /dev/mapper/data_disk_ESFH      3.11TiB
   /dev/mapper/data_disk_EVPC      3.11TiB
root@phoenix:~#

root@phoenix:~# btrfs --version
btrfs-progs v5.1


I presume running another balance will fix this, but surely all metadata
should have been converted?  Is there a way to only balance the DUP
metadata?