What happens if I have two Memory Makers on my account at the same time?

[basketlacey]

We are going down on 7/4 and staying 1 night on site (dolphin), 1 week off site, followed by 4 nights at OKW using the AP rate with the free MM package. I understand the free MM won't be active until I check in on that reservation. So, I plan to purchase MM to use for the whole trip and "save" the AP one for our next trip in September. Can I do this?