React KeyCloak : keycloak js header Access-Control-Allow-Origin sent twice in response

Hello I now integrate keycloak with my react app.

We admin the server to deal :

- //localhost:xxxx
- //xxxxxx.xxxxx.net
with the same domain as our keycloak server

With the second link  //xxxxxx.xxxxx.net we got the error

 we get CORS error : 

Access to XMLHttpRequest at '//sso.xxx.net/auth/realms/xxx/protocol/openid-connect/token' from origin '//yyyy.xxx.net' has been blocked by CORS policy: The 'Access-Control-Allow-Origin' header contains multiple values '//yyyy.xxx.net, //yyyy.xxx.net, but only one is allowed.
keycloak.js:750          POST //sso.xxx.net/auth/realms/xxx/protocol/openid-connect/token net::ERR_FAILED 200

 With the first link //localhost:xxxx all is working fine.

The main difference I could see is in the two requests for cors in the request headers:

With the first link //localhost:xxxx

Sec-Fetch-Mode: cors
Sec-Fetch-Site: cross-site

With the second link //xxxxxx.xxxxx.net 

Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-site

Thanks for your help