Same cookie appears on two difference servers

We have cookie persistence set up on the F5. If the cookie includes the IP of the server that the session resides on, how can the exact same cookie appear on two different servers within 4 minutes? Product BIG-IP Version 11.5.4 Build 2.0.291 Edition Hotfix HF2

ltm persistence cookie cookie { app-service none cookie-name none expiration 0 hash-length 0 hash-offset 0 method insert mirror disabled

ltm rule secure_httponly_cookie { when HTTP_RESPONSE { set myValues [HTTP::cookie names] foreach mycookies $myValues { if { [HTTP::cookie version $mycookies] != 1 } { set ckval [HTTP::cookie value $mycookies] set ckpath [HTTP::cookie path $mycookies] HTTP::cookie remove $mycookies HTTP::cookie insert name $mycookies value $ckval path $ckpath version 1 } HTTP::cookie secure $mycookies enable HTTP::cookie httponly $mycookies enable } } } As we reviewed the splunk logs, we have found multiple instances where the same request ends up at different servers for the same session id. This defeats the Session Affinity (Cookie persistance) that is required by the application and will cause Session Timeout issues. See the picture below showing two servers with the exact same cookie. Any suggestions or links on how to address would be appreciated.