How can I remove a <none> tag without deleting the docker image itself?

Every time I pull an image, there are two tags pulled. Like this:

centos  6       f07f6ca555a5  4 weeks ago  194.6 MB  
centos  <none>  f07f6ca555a5  4 weeks ago  194.6 MB

How can I remove the later tag only?

$ docker info
Containers: 2
 Running: 0
 Paused: 0
 Stopped: 2
Images: 13
Server Version: 1.12.1
Storage Driver: aufs
 Root Dir: /mnt/sda1/var/lib/docker/aufs
 Backing Filesystem: extfs
 Dirs: 181
 Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge overlay host null
Kernel Version: 4.4.17-boot2docker
Operating System: Boot2Docker 1.12.1 (TCL 7.2); HEAD : ef7d0b4 - Thu Aug 18 21:18:06 UTC 2016
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 7.604 GiB
Name: default
ID: WUS6:YHEN:O4U4:6GYZ:ECIX:5KQA:SAYJ:HNPY:RJB4:AEMR:QQCE:777M
Docker Root Dir: /mnt/sda1/var/lib/docker
Debug mode (client): false
Debug mode (server): true
 File Descriptors: 14
 Goroutines: 23
 System Time: 2016-10-10T02:13:57.107136165Z
 EventsListeners: 0
Registry: https://index.docker.io/v1/
Labels:
 provider=virtualbox

docker rmi $(docker images --filter "dangling=true" -q --no-trunc) This command is not working for me. Actually they are the same image.

Solution

This is actually a 1.11.2 bug, reported in issue 23895 and issue 23503.
It is supposed to be fixed in 1.12.x, with PR 23549: "Do not show empty tags for digest references in output".

When a repository has a tag and digests, show tag for each digest value.
Rows will not be duplicated for the same image name which has both a tag and a digest.

If you still see this in 1.12.1, you should open a new issue, as it might be a regression from 1.12.0.