An interesting thing to note, since the white dice can both be used, you can statistically skew the bonus they provide by giving priority.
Consider this mech:
You don't have any valid spot targets, since they are all out of range/behind cover. You are trying to get to an objective, but you know this guy is going to get railed on.
while

= 4.4722

=4.4722
If you consider that you give the higher of the

to one and the lower to the other the numbers change.
the priority counts as having the same effect as 3d6 pick highest, so it gets an average of 4.9583
the non-priority is 2d6 pick lowest, then roll 1d6 and pick highest, getting an average of 3.99
Of course this is just looking at the odds differently. It less you say, I'm going to prioritize X, and give the rest to Y