There's really only one scenario where it's likely the SEC would get two teams into the playoff:
Alabama, Ole Miss, and Mississippi State end up in a three-way tie for first place in the SEC West with Bama convincingly beating Mississippi State (though perhaps not a blow-out), Ole Miss losing a nail-biter to Mississippi State to close out the season, and Bama winning the SEC Championship Game.
If this were to happen, we are all but assured of representing the West in Atlanta due to the new tie-breaker rules which would almost certainly eliminate Ole Miss first, giving us the berth due to our head-to-head result over Mississippi State.
It would be extremely difficult for the committee to leave out an SEC Champion, 12-1 Alabama team - especially since several of the members have openly promoted the idea that Conference Championships are very important. At the same time, you'd have an 11-1 Ole Miss team sitting out there that actually beat Alabama on the field. Assuming that FSU goes undefeated, you could end up with a scenario like this for the committee to consider:
Playoff Spots:
1. FSU
2. Bama
3. ???
4. ???
In serious contention for the last two spots:
12-1 Oregon, PAC 12 Champions
12-1 Michigan State, B1G Champions
11-1 Ole Miss
11-1 Mississippi State
Mentioned but not really in serious contention:
10-2 Kansas State, Baylor, TCU, or West Virginia Big 12 Champion
10-2 Notre Dame
I think, in this scenario, Oregon is pretty much a shoe-in for the third spot. The fourth spot, though, gets tricky.
1. I don't think anyone in the Big 12 is going to escape without a second loss, the way the schedules stack up, and you've got a good shot at a three-way tie there as well.
2. Notre Dame's second loss, which I think comes against Arizona State, puts them out of contention since they'll have lost half of the only real games on their schedule.
3. Michigan State would seem like a good choice but they've already been beaten by one team either in the playoff or at least in contention for a spot. Plus, they play in the B1G which makes their 12-1 record the least impressive one-loss resume.
4. Mississippi State, fresh off a win over then #1 or #2 Ole Miss, boasts a pretty good resume but has already lost convincingly to an Alabama team assured of making the playoff.
5. Ole Miss had the misfortune of losing their last game of the regular season which might drop them out of contention, however, that loss was a nail-biter to their in-state rival and they do have a win over a team assured of making the playoff.
6. Only four teams either assured of getting or in serious contention for a playoff spot will have beaten another team either assured of getting or in serious contention for a playoff spot:
- Alabama, over Mississippi State
- Oregon, over Michigan State
- Ole Miss, over Alabama
- Mississippi State, over Ole Miss
... and of those wins, the Ole Miss victory over Alabama is clearly the best win.
7. Of the four teams in serious contention for the last two spots, their losses ranked from "best" loss to "worst" loss are probably:
- Michigan State to Oregon
- Ole Miss to Mississippi State
- Mississippi State to Alabama
- Oregon to Arizona
...and you could make a good argument for swapping those first two as well as, perhaps, swapping the last two since injuries played a not-insignificant part in Oregon's loss.
8. Given that Mississippi State's best win isn't the best of the four and that their loss to Alabama clearly isn't the best loss, it's hard to see them getting in over Ole Miss - whose best win and loss are both clearly better than Bulldog's - even though they did beat them.
9. There could be some sentiment within the committee to avoid a "but we beat Bama" versus "but we beat Ole Miss" argument between Ole Miss and Mississippi State supporters, respectively, by leaving both out in favor of another, Conference Champion team. This would, obviously, give an advantage to Michigan State.
So, you really end up with the committee's choice being between:
A) Putting in a second SEC team, Ole Miss, which is likely the most deserving team with the best resume among those in contention or
B) Putting in a Conference Champion, Michigan State, which has already lost to another team in the playoff and has the weakest resume among those in contention.
Either choice presents the opportunity for a rematch, so that potential "tie-breaker" goes out the window. It would all come down to whether or not the committee wants to put an obviously weaker team into the playoff over a second SEC team, thereby setting a precedent that a Conference Championship is worth more than another team's overall resume.
If they were to do that, it would potentially hurt the SEC's chances of winning the National Championship this year as well as its chances of getting two teams into the playoff in any given year but would most likely help the SEC's chances of winning the National Championship in any given year even more; in any given year we are more likely to end up with a two-loss SEC Champion than with two (or more) teams under serious contention for a playoff spot.