- 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))

  - A `create` or `update` API request with duplicate items in a keyed list no longer wipes out managedFields. Examples include env var entries with the same name, or port entries with the same containerPort in a pod spec.

- 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...

- 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))

#### Cluster Autoscaling
* Cluster Autoscaler 0.6. More information available [here](https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/README.md).

* cluster-autoscaler: Fix duplicate writing of logs. ([#45017](https://github.com/kubernetes/kubernetes/pull/45017), [@MaciekPytel](https://github.com/MaciekPytel))


#### Cloud Provider Enhancement

* AWS:

- 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

- Duplicate owner reference entries in create/update/patch requests now get deduplicated by the API server. The client sending the request now receives a warning header in the API response. Clients should stop sending requests with duplicate owner references. The API server may reject such requests as early as 1.24. ([#96185](https://github.com/kubernetes/kubernetes/pull/96185),...

* [fluentd-gcp addon] Update Stackdriver plugin to version 0.6.7 ([#52565](https://github.com/kubernetes/kubernetes/pull/52565), [@crassirostris](https://github.com/crassirostris))
* Remove duplicate proto errors in kubelet. ([#52132](https://github.com/kubernetes/kubernetes/pull/52132), [@adityadani](https://github.com/adityadani))

- KEP-1880: Users of the new feature to add multiple service CIDR will use by default a dual-write strategy on the new ClusterIP allocators to avoid the problem of possible duplicate IPs allocated to Services when running skewed kube-apiservers using different allocators. They can opt-out of this behavior by enabled the feature gate DisableAllocatorDualWrite. ([#122047](https://github.com/kubernetes/kubernetes/pull/122047), ...

- Fixed a bug that caused duplicate validation when updating a ReplicaSet. ([#131873](https://github.com/kubernetes/kubernetes/pull/131873), [@gavinkflam](https://github.com/gavinkflam)) [SIG Apps]