Unable to create multiple WBS elements in a single S/4 Hana API API_ENTERPRISE_PR call using Postman

[aj372]

I am able to create a single WBS element for an enterprise project through the S/4 Hana public cloud API call by passing the request Json through Postman as below.

But I am unable to create 2 WBS elements in a single S/4 Hana API call using Postman by passing the below json request as in the image below

Error response is as below

Please suggest how I can mitigate this issue.