You are using a Data store Operation of the type Write.

In a Data Store Write operation:

If multiple messages are written with the same Entry ID, enabling Overwrite Existing Message ensures that the previous entry is replaced, avoiding duplicate records.

Other options:

Encrypted Stored Message → Secures data, not related to duplicates.

Include Message Headers → Controls storage of headers, not duplication.

Retention Threshold for Alerting → Configures alerts, not duplication.

Thus, the parameter required to avoid duplicates is Overwrite Existing Message.