Curl post same json to gateway produce 2 distinct saved json

hi all
i’m doing bulk insert document with :
curl -X POST -d @myJsons.txt http://localhost:4984/myDb/_bulk_docs --header "Content-Type:application/json"

it works but if i redo curl , result is duplicated jsons. how to avoid it using curl?

What is the JSON that you are sending up in the body of the request? Note that per!/database/post_db_bulk_docs
"… add new documents, you can either specify the ID (_id) or let the software create an ID. To update existing documents, you must provide the document ID, revision identifier (_rev), and new document values. "

If you are not providing an ID, then the two requests will result in two new documents being created