One of the steps in the AA program states that one is to make amends for harms he has done. This is not done for the others, but for him/herself. A person who leads a double life is a tormented person, and the person who is tormented may be inclined to drink to relieve his discomfort.
If one has behaved like a self-centered jackass in the past, he can be in denial and make excuses to suppress his conscience -- "He deserved it," "It didn't do any harm," "Nobody knows about it," and similar thoughts may pass through his mind, though a part of him knows better. While he is engaging in double-think to try to feel better, he is pulling himself in two directions.
I have heard remarks to the effect that making amends only applies to things one did while he was drinking. No, it just applies to things he did, period.
He can feel a pang of conscience for things he did before he ever took his first drink, in sober periods in his early drinking days, and even since he quit. So long as he remembers a wrong he has done, it will bother him on some level, whether he is consciously aware of that or not. (The exception is the psychopath, who isn't bothered by any wrong he does, no matter how serious.) We can assume that you are not that, since nearly all people are not.
A person who has not had a drink in years, and then who cheats someone in a business deal risks his own sobriety. He does himself a service not to do that, and if he does do it, to make it up somehow. This can be tricky at times.
A common quandary is of one who has cheated on his/her spouse or somebody else's spouse. If you apologize to somebody who knew nothing about it, you risk creating more trouble and more misery than if you had said nothing. Your amends might be to not do that again, and perhaps be good to the other person in a way unrelated to the wrong done.
One might ask what to do if the person he offended is dead, or has moved to parts unknown. Possibly he can make amends in his own mind by contributing to a charity or to the other's dependents in a way he would have wanted. In that case, give til it hurts, to be certain one hasn't cut corners and failed in some part of his mind to compensate for the wrong.
To repeat myself, the person isn't doing it for them. He's doing it for himself.