Angular 5 HttpClient Access-Control-Allow-Origin header mulptiple value

Question

I have a Angular 5 application where i use simple GET request

public getData(url: any): Observable<any> {
    return this.HttpClient.get(url).
        .map((res) => res)
}

when i send request to server with http protocol - everything working ok (and in network tab of my chromium browser i see only one Access-Control-Allow-Origin: http://127.0.0.1:4200 ), but if i send request to https protocol to same server - i have error:

The 'Access-Control-Allow-Origin' header contains multiple values 
'http://127.0.0.1:4200, *', but only one is allowed.

If open network tab - there we can see really two Access-Control-Allow-Origin:

Access-Control-Allow-Origin: http://127.0.0.1
Access-Control-Allow-Origin: *

How i an leave only one origin and why it happens when i use https? Now i cant change CORS on backend :(

From server side - GeoServer on nginx.

My nginx CORS config:

add_header 'Access-Control-Allow-Origin' '*';
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range';
add_header 'Access-Control-Expose-Headers' 'Content-Length,Content-Range';

Answer 1

include this in your web config file.

   <httpProtocol>
          <customHeaders>
            <add name="Access-Control-Allow-Origin" value="*" />
            <add name="Access-Control-Allow-Headers" value="Content-Type, X-Your-Extra-Header-Key" />
            <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE,OPTIONS" />
          </customHeaders>
        </httpProtocol>

Let me know in what language you written your API functionality.