Use a proxy, you might be able to get away with it for a time if you are really careful with everything. And not just those free ones. There are cheaper proxy services that allows you use of hundreds of unique IPs.
Goodle Strictly Probhited that, same id tow adsense, even if they copught same person have two accoutn even if different id they will suspend you
I agree with you. You can check your adsense account and also your friend can check account with same IP but you both are not allowed to click on each other ads link.