There is something of a "chicken and egg" scenario with nominations and appointments that can get quite complicated.
Assuming a "typical" candidate, such as the OP seems to be, there are four nominating sources: District MOC, Senator 1, Senator 2, and VP. In this scenario there are 3 categories of appointment with 6 opportunities for appointment: 4 as slate winner, 1 as Qualified Alternate, and 1 as Additional Appointee. Of those only the Additional Appointee can be appointed out of Order of Merit and the majority of these are recruited athletes and diversity candidates.
Appointments are not made because a candidate fits into multiple categories. The juggling of appointment categories takes place
after appointment. It makes admissions job easier, but does not replace the WCS score as arbiter of appointment decisions.
A strong candidate has significantly increased odds by competing on multiple slates - think of it as playing multiple hands of Blackjack.
A weaker candidate ranked near the bottom of each slate does not have
significantly increased odds of appointment - one in 20 million really doesn't affect my life any more than one in 100 million. When I buy a bunch of lottery tickets my next stop is not the Ferrari showroom.
Bottom line: Get all the nominations you can because you don't know whether you are that strong candidate or the weaker one. You also don't know if one of those slates is significantly weaker or if the MOC's are coordinating.