Hi @AK,
The issue here is because of when the SSRS web portal reloads inside itself instead of just rendering the report content. It usually occurs if a reverse proxy, ARR or URL rewrite rule is redirecting report content requests back to the portal home page. Please follow below steps:
If using ARR, reverse proxy, load balancer or URL Rewrite in front of SSRS, enable Reverse rewrite host in response headers in ARR settings and ensure host headers are preserved.
Make sure no rule rewrites /reports or /reportserver requests to /reports/home.
If you are not using a proxy, verify the Web Portal URL and Report Server URL match exactly in Reporting Services Configuration Manager.
Restart the SSRS service after making the configuration changes.
After correcting the URL or proxy configuration, the duplicate header issue will not occur.
Thanks,
Anjan Kumar Chippa