I think that two weeks is still early days. It may also be that there will always be a situation between the two of them in which the one needs to express dominance over the other. It doesn't mean they are fighting - it's just a natural cat social thing. As long as they are not hurting each other, I wouldn't worry. They will work things out to whatever extent they are going to work things out. It may not suit your dream relationship for them, but when it comes right down to it, you really can't create the way in which they will relate to each other. You have done the right thing in separating them while you are not there, and keeping an eye on them while you are. I have always found it the easiest to adopt two cats together, so one does not establish a sense of territory before the other one comes - but even so, I have found that one develops a sense of dominance, usually right away.