OK... Let me see if I understand what you are proposing/asking. Are you asking if it is possible for 2010, to select SWU as a Platinum choice benefit and receive 4, and then select SWU TWICE as your two options for your Diamond Choice benefit and receive an additional 12 SWUs for a total of 16?

In essence, you want to know if a Diamond member can select the same choice benefit twice, instead of two unique benefits. Is that right?

My "unofficial" guess would be NO. But then again, if you could use all 16 SWU because you are flying on that many International Y, B, and M fares, I would say Delta needs more customers like you.