No, you cannot train 2 skills in a week. You can only train 1 skill in a week.
So say you set your training as JS (for wingmen)on Monday and on Tuesday's league game, you play him as a SF and get him 48 minutes as a SF. Then on Wednesday you change the training to JR (one position at SG) and on Thursday's scrimmage game, you play him as a SG and get him 48 minutes as a SG.
In this case, the skill that will be trained will be the JR because that was the skill which was set before the training update. So despite the fact that you've played him as a SF when the training was set for JS for wingmen, because you have changed to the training to JR, the only skill that will be trained will be the JR, not JS.