User Can not trying login more 1 times by external captive portal

Please help me because I searched allot about this problem without  result .

I have external captive portal with url :

10.10.0.31/Radius/index.php 

now when user trying to access internet he will redirecting to captive portal url so the url of login page will be like this 

http://10.10.0.31/Hotspot...33.1:1000/fgtauth&magic=0101048fcaf307fa&usermac=54:ab:3a:fc:37:a8&apmac=08:5b:0e:01:b3:fa&apip=192.168.33.1&userip=192.168.33.2&ssid=port1&apname=FGT60D4613007825&bssid=00:00:00:00:00:00&device_type=windows-pc

now when user insert wrong username or password he must retry again ,but when user trying again  the request not send to fortigate or fortigate not processing this request until user has new magic id so he must  write into url any website url {www.google.com for example} and he will redirect to login page again with new magic id and he can retry again 

but I don't want that , I want user to trying many times 

in other word user can not sent login request more than 1 time with same magic id 

how can I solve this problem . please help me