I don’t think that there’s any issue with doing aerobic and anaerobic work on the same day. In fact, on high intensity days, I always include lower intensity as well. I’d be inclined to reverse the order that you mentioned though.
If I have any high intensity work to do, I typically do that first, when I’m fresher, in order to get the most quality out of the workout. Plus, following intensity with lower end aerobic work allows your body to reabsorb the lactate that it’s created.
In Olbrecht’s, The Science of Winning, he talks about this same thing, following high intensity work with low intensity as an add-on aerobic capacity exercise (i.e. training the body to reabsorb lactate).