disk information display error when perform volume multiattach

Issue description:

1.When I perform volume multiattach and check volume information on dashboard, there is wrong disk information.

Versions and Components

- Dashboard: stable/queens
- OS: Ubuntu 16.04.6 LTS
- Python: Python 2.7.12
If you use rocky release, you may also succeed to reproduce it.

Steps to reproduce:

1. create multiattach volume type: openstack volume type create --property multiattach="<is> True" matt
2. create a volume of multiattach volume type: openstack volume create --size 1 --type matt m1
3. perform multiattach(where cirros1 and cirros2 are instances created by openstack, f5966dde-7724-4c1c-8b43-7b98971de582 is the id of m1): nova volume-attach cirros1 f5966dde-7724-4c1c-8b43-7b98971de582;nova volume-attach cirros2 f5966dde-7724-4c1c-8b43-7b98971de582
4. log in horizon and click Project/Volumes/Volumes and find the volume m1 and click drop-down menu and click Manage Attachments, you will find disk information display error.

Expected:

1. On instance cloumn, there are cirros1 and cirros2

Actual:

1. On instance cloumn, there are cirros1 and cirros1 or cirros2 and cirros2, that is to say,they are same.

The issue:

1.In addition, I also faced the same question when i attach ceph muliattach volume to multiple instance.