I think it's a case to case basis, since each person is different. It is quite common though, to trade one addiction for another. I'm glad that you were able to stay clean for a year, although try not to be too addicted to the internet, since too much of anything is not productive and can be harmful in general.
Addiction is giving in to cravings, so if you give up one addiction, your body will crave another one and you will obsess on it until you give in. That's the thing with addiction, it never goes away on its own. You have to be the one to drive it away, and you have to be strong enough to keep it out when you have successfully driven it away from your life because, it will come back, in one way or another, and you need to repel it every single time.
Hmmm... I'm trying to think if I did replaced my addiction with another one. I remember craving so much chips back when I was starting into my recovery. From Lays, to Ruffles, to Pringles... I wanted them all. It didn't help that even before my recovery, I loved chips. I'm glad though that I changed my lifestyle into a more healthy one and I have quit this unhealthy addiction as well. Right now, I can say that I'm free from any addicting substances. But sadly, I have gotten addicted to work, work, work, work... I think I've become a workaholic, working from night until the noon of the next day. Is that a bad thing? I barely get enough sleep as well. Although I do eat a lot of fruits and vegetables so that's one up side. I stay hydrated as well by drinking water. I guess there's some truth to this theory, at least for me. I just get so into whatever I'm doing, be it work, hobby or eating. It's hard for me to control myself as well.