Who is assigning the static IP? If it's your ISP, depending on how they assigned it, will depend on whether or not you can change it. If you clone your MAC and it doesn't change, then you have your answer. In any event, if you change your IP and can still connect to the internet, you're fine unless your ISP doesn't want you to have the new IP. In that case, they'll reset your connection and assign you the IP they want you to have.