Can we use two different seed options to generate 5M streamlines contributed from each option

Command :

tckgen -act 5tt_coreg.mif -backtrack \
$wmFOD $tckFName -seed_gmwmi gmwmi.mif -seed_image maskImage.nii.gz -select 10M -cutoff 0.05 --force

Queries :

1.Can we use two different seed options (seed_image and seed_gmwmi ) in one tckgen command run?

a) If yes does the order of the seed options influence the outcome ?

b) Can we generate the 10M streamlines, with 5M streamlines contribution from each option?

2.Generating 5M streamlines separately with the above seed options and merging both would be equivalent to above mechanism ?

3.Which above approaches could be efficient technically, if next step was to use tckedit with SIFT2 based filtering?