Problem of registering fake a lot in ojs2

My journal use ojs2, and recently I have so problem from fake users. I dont know wthat can I do for stop this.
users fake register so easily whatever we have captcha code and email validation for registering.
May be help me?

Thanks you for your time and help

captcha in ojs 2.x it is easy to break. you should change a re-captcha.