IIS 8.5 and tomcat, doubles status code

IIS 8.5 and tomcat with isapi redirect
if goes through iis doubles status code

with iis

curl http://localhost/docs/ -i

HTTP/1.1 200 200
Content-Length: 17096
Content-Type: text/html
Last-Modified: Fri, 05 May 2017 09:03:42 GMT
Accept-Ranges: bytes
ETag: W/"17096-1493975022000"
Server: Microsoft-IIS/8.5
X-Powered-By: ASP.NET
Date: Wed, 07 Jun 2017 06:37:29 GMT
Connection: close
...

direct:

curl http://192.168.10.10:8080/docs/ -i

HTTP/1.1 200
Accept-Ranges: bytes
ETag: W/"17096-1493975022000"
Last-Modified: Fri, 05 May 2017 09:03:42 GMT
Content-Type: text/html
Content-Length: 17096
Date: Wed, 07 Jun 2017 06:49:42 GMT
...

isapi configuration

workers.properties

worker.list=expc

worker.expc.port=8009
worker.expc.host=192.168.10.10
worker.expc.type=ajp13

worker.expc.lbfactor=1

uriworkermap.properties

/docs/*=expc

which could be the cause for this. thank you