1. Each of those nominations you received, puts you on a list of 10 names, and that list has 1 guaranteed appointment coming from that list. So in your case, you have 2 chances of receiving an appointment because you are on 2 lists.
2. If however, the senator/representative ranks that list in any of 2 ways, (Which most senators/representative DON'T Rank their list), then unless you are the #1 on that list, you won't receive an appointment unless all those ranked ahead of you somehow become disqualified or turn down the appointment.
3. If the senator/representative doesn't rank the list, then the academy will choose from that list you are on, based on who they believe (Based on total score of their application), the one to receive the appointment. So basically; you could be on 10 lists, but unless you are the BEST on that list, you won't receive an appointment.
4. For all those who have nominations and don't receive an appointment based on the guaranteed slot from that list as I mentioned earlier, you will be placed on a "NATIONAL" list. On that list, it doesn't matter if you have 1 nomination or 10 nominations. Your name is on the list only once. The difference however is that between 1/3 and 1/2 of all appointments actually come from this "National" list. Therefor, your chances may actually go up compared to who you are competing against.
And that is what really matters. "WHO IS YOUR COMPETITION"? In theory, 2 nominations give you 2 chances, "Outside of the national list", to receive an appointment. But you could be #10 on each of those lists. The other 9 on each list could have so much better of an application. On the other hand, you could be the 2nd best in your district/state applying, and if the #1 accepts an appointment from one of the nomination lists, that would give you a great chance of getting the appointment from the other list. Best of luck.