Different Tech has different ways of accepting the parameter passed. This is because there is no RFC or anything defined for this.

  • We usually see this in loads of Password reset functionality that if we send a requests with multiple email then only the first one is considered.

    html email=victim.com&email=attacker.com

  • If in the URL the & or any other character is not encoded then the possibility is high that if you add a new value then it will be accepted.

  • PHP usually consider the last occurrence