I need to run two new 20A circuits to the other side of the house - at Home
Depot I see this "12-2-2" romex cable with 2 hots, 2 neutrals, and one
ground. Is it safe to share that one 12ga. ground between two 20A
circuits? (I "assume" it was a 12 ga ground, it's up in the air on the
spools at HD so hard to get a close look)

Does 12/4 armored cable (MC or BX) only have one grounding conductor? or is
it better because the metal jacket is an additional/supplemental grounding
path?

Thanks.