Beers, you're focussing on the wrong thing. Let your coach try to establish the increments in your favor. That will be in advance of the meet. Once the meet starts, the rules are as RG stated. You should not fret or worry over this - let your coach handle it.
You need to start focussing on how you're going to get one of the 2 state slots. You only need to beat 1 of the other two 13-6 contenders to qualify.
Unless I missed something, your priorities should be something like this (in priority order):
1. Get 1st or 2nd in the meet.
2. Win the meet.
3. Get a PR.
So how do you meet priority #1? Well ... it will depend on many factors that I'm not aware of... but it goes something like this (in random order) ...
1. With 3 of you at 13-6 now, and all of you unlikely to hit 14-0, and 6-inch increments between jumps, it sounds highly likely that there will be ties to break (by counting misses).
2. Just
ASSUME that the 3 of you will tie at 13-6. Don't WORRY about this possibility. Instead, just
ASSUME it before the meet even starts. Then you're ready for it. That puts your focus during the meet on minimizing misses. And even if you all tie at 13-0 (bad weather), or all tie at 14-0 (tailwind), then this logic is still sound.
3. Don't start too high, and don't start too low. Start at a height that you KNOW you'll make, but not ridiculously low. Recall how many jumps you've taken in past meets, and what jump number seemed to be your best jump. Work out your starting height from there, so that you'll go 13-6 for sure, and still have enough energy left for 14-0.
4. If you're going in 6" increments, after your opening height, don't pass any more heights (unless you started ridiculously low). It's better to clear on first try than to pass and then clear on 2nd or 3rd try. Depending on how many vaulters there are, taking each height keeps you warm (and keeps your confidence up) consistently thru the meet. If you pass, you might have too long to wait for the next height.
5. Keep a written record of the makes/misses of the other contenders. Don't rely on memory, and don't rely on peeking over the official's shoulder. Have the sheet prepared ahead of time, and just fill in the vaulting order as soon as you know it. If you can get your coach to do this for you, so much the better.
6. Make sure you're thoroughly warmed up before each vault (assuming that there might be lots of waiting time). It's far better to lose a bit of energy by extra warmup between each jump than to jump cold and miss.
7. The name of the game is to miss as few times as possible.
8. If you get behind on misses, then don't worry. just keep jumping well, and you'll beat them at 14-0. You'll HAVE to, right? So you WILL!
9. If the other contenders clear 14-0, then don't worry. They did it ... and they're no better than you ... so YOU can do it too! Always think positively!
Good luck!
I'm sure there's some other ideas that I've forgotten (or I'm not even aware of). These are just some random ones, off the top of my head.
Kirk