After doing live migrations for some instances, and those migrations failing, the attached volumes show duplicates of the same attachment. 

This is the error message I get when the migration fails:

openstack volume list shows the volume is attached to the instance twice.

| a424fd41-a72f-4099-9c1a-47114d43c1dc | zktech-wpdb1            | in-use    |   50 | Attached to ead8ecc3-f473-4672-a67b-c44534c6042d on /dev/vda Attached to ead8ecc3-f473-4672-a67b-c44534c6042d on /dev/vda

How do I remove the duplicate attachment, and why could the live migration be failing in the first place? Not all migrations fail, but sometimes they do and I have multiple volumes with duplicate attachments.