737 Incog,
True, you could engineer that situation if your alternates are further than your destination and alt 1 and alt 2 are distant from each other. Or if you choose alternates carefully then if the destination doesn't open you could make an approach to Alt 1, divert to Alt 2 and arrive with more fuel than if you'd made an approach at the destination and then diverted to Alt 2.
To write a rule to cover all eventualities would be very cumbersome and the final say on choice of alternates and fuel to carry is down to you as the captain.
If you really want to be covered, produce 2 plogs. 1 to dest with 2 alternates and using fuel for the farthest. The second to Alt 1 using Alt 2 as the alternate. Then use the higher of the 2 fuel loads.
Beakor