S3 deduplication

S3 natively don't have de-duplication feature built in. There are multiple solutions from partners which can be used to achieve de-deduplication. e.g. https://aws.amazon.com/blogs/apn/cloud-deduplication-on-demand-storreduce-an-apn-technology-partner/

Deduplication is not a feature of Amazon S3. Deduplication requires a database to track parts (which can impact durability), and typically trades storage capacity for compute and IO. In addition, deduplication must operate above any encryption layer, potentially reducing security.

Products that use Amazon S3 (backup partners, storage partners such as NetApp ONTAP, etc.) can of course apply their own deduplication prior to writing to Amazon S3.