Problem with copying image to a new one with the help of Buildx and then assign a new tag

[JustinDroege]

Currently we using this following command in order to create a "new" image with the manifest of an existing image:

docker buildx imagetools create localhost:5000/example:1 --tag localhost:5000/example:2

Later we want to give the image example:2 a new tag. With this following command:

docker tag localhost:5000/example:2 localhost:5000/example:3
docker push  localhost:5000/example:3

Now when we compare all hashes, we will see that example:3 has the same hash like example:1 but i would expect that example:3 has the same hash like example:2. I received the hashes with this command:

docker buildx imagetools inspect localhost:5000/example:1

And here is the result output for all three of them:

example:1

Name:      localhost:5000/example:1
MediaType: application/vnd.docker.distribution.manifest.v2+json
Digest:    sha256:491d583dc4f715419e70da4c9bb93a5d67e218065fa614fe2396edcba3c59c41

example:2

Name:      localhost:5000/example:2
MediaType: application/vnd.docker.distribution.manifest.list.v2+json
Digest:    sha256:a51dd10528bb0faa30d635c785461fda68fea7aafb0f8d232784d9fb9ae34654

Manifests:
  Name:      localhost:5000/example:2@sha256:491d583dc4f715419e70da4c9bb93a5d67e218065fa614fe2396edcba3c59c41
  MediaType: application/vnd.docker.distribution.manifest.v2+json
  Platform:  linux/amd64

example:3

Name:      localhost:5000/example:3
MediaType: application/vnd.docker.distribution.manifest.v2+json
Digest:    sha256:491d583dc4f715419e70da4c9bb93a5d67e218065fa614fe2396edcba3c59c41

We can see that example:1 and example:3 have the same hash: 491d583dc4f715419e70da4c9bb93a5d67e218065fa614fe2396edcba3c59c41
but i would expect it should have the hash: a51dd10528bb0faa30d635c785461fda68fea7aafb0f8d232784d9fb9ae34654

Do i have a wrong understanding of this behaviour?