because you haven't watched tutorial maybe,you should have your profile renamed to user1 and secodn profile to user 2,then you will not loose saved data,but I'm still little afraid that it will fuck my system up
It's perfectly safe, I tried it more than one time and linked both my Desktop, and Laptop. To be safe not to loose any data make sure you only have two users (USER1, USER2) any other user will be deleted.