- A server-side apply request that changes an object which has duplicate items in a keyed list, and modifies the duplicated item removes the duplicates and replaces them with the single item contained in the server-side apply request. ([#121575](https://github.com/kubernetes/kubernetes/pull/121575), [@apelisse](https://github.com/apelisse))

* The Rackspace cloud provider has been removed after a long deprecation period. It was deprecated because it duplicates a lot of the OpenStack logic and can no longer be maintained. Please use the OpenStack cloud provider instead. ([#52855](https://github.com/kubernetes/kubernetes/pull/52855), [@NickrenREN](https://github.com/NickrenREN))

* Made multi-scheduler graduated to Beta and then v1. ([#38871](https://github.com/kubernetes/kubernetes/pull/38871), [@k82cn](https://github.com/k82cn))
* Fixed forming resolver search line for pods: exclude duplicates, obey libc limitations, logging and eventing appropriately. ([#29666](https://github.com/kubernetes/kubernetes/pull/29666), [@vefimova](https://github.com/vefimova))

- kube-apiserver `--admission-control-config-file` files are now validated strictly (EnableStrict). Duplicate and unknown fields in the configuration will now cause an error. ([#128013](https://github.com/kubernetes/kubernetes/pull/128013), [@seans3](https://github.com/seans3))

- kube-proxy: a configuration file specified via `--config` is now loaded with strict deserialization, which fails if the config file contains duplicate or unknown fields. This protects against accidentally running with config files that are malformed, mis-indented, or have typos in field names, and getting unexpected behavior. ([#82927](https://github.com/kubernetes/kubernetes/pull/82927), [@ob...

* [fluentd-gcp addon] Update Stackdriver plugin to version 0.6.7 ([#52565](https://github.com/kubernetes/kubernetes/pull/52565), [@crassirostris](https://github.com/crassirostris))
* Fixes an issue with RBAC reconciliation that could cause duplicated subjects in some bootstrapped rolebindings on each restart of the API server. ([#53239](https://github.com/kubernetes/kubernetes/pull/53239), [@enj](https://github.com/enj))

- Fixed a bug that caused duplicate validation when updating `PersistentVolumeClaims`, `VolumeAttachments` and `VolumeAttributesClasses`. ([#132549](https://github.com/kubernetes/kubernetes/pull/132549), [@gavinkflam](https://github.com/gavinkflam))

* Fixes an issue with RBAC reconciliation that could cause duplicated subjects in some bootstrapped rolebindings on each restart of the API server. ([#53239](https://github.com/kubernetes/kubernetes/pull/53239), [@enj](https://github.com/enj))

- Manual change of a failed job condition status to False does not result in duplicate conditions ([#110292](https://github.com/kubernetes/kubernetes/pull/110292), [@mimowo](https://github.com/mimowo)) [SIG Apps]
- OpenAPI will no longer duplicate these schemas:
  - io.k8s.apimachinery.pkg.apis.meta.v1.DeleteOptions_v2
  - io.k8s.apimachinery.pkg.apis.meta.v1.ObjectMeta_v2

- Fixed a regression in default configurations, which enabled PodDisruptionConditions by default, 
  that prevented the control plane's pod garbage collector from deleting pods that contained duplicated field keys (env. variables with repeated keys or container ports). ([#121380](https://github.com/kubernetes/kubernetes/pull/121380), [@mimowo](https://github.com/mimowo)) [SIG Apps, Auth, Scheduling and Testing]