It really depends upon the time that you have to put into studying. It can be done if you have plenty of time, don't have a family, and have good memorization skills. However, it will be tough.
This semester, I was taking just A&PII and Microbiology. I had a hard time balancing the two; A&P and Micro are very different topics, and there was just too much to memorize between the two. However, there were other students who didn't have kids and were able to spend more time studying. These students have lower grades than I do in A&PII (since I now only have one class), but they are still passing both. It also depends upon the difficulty level of your instructor. My Micro teacher was incredible hard, and we had to memorize how to spell each microorganism. She's a good teacher, and I will take her again next semester, but it was too much with A&P.
You can always register for both, give it a try, and drop before the last day to withdraw if you are not doing well. One more thing to consider: If your nursing program accepts students based upon a points system, you might want to see if you are penalized if you score below a certain grade.
In retrospect, I would not take both classes at the same time. However, I do know people who are doing it now. I know that's not really helpful, but I hope it might give you a little bit of inside information.