With two fathers, there would be 50% chance of having a normal male offspring, 25% chance of having a female, and 25% chance of a YY non-viable egg. With two mothers, they would all be normal female offspring without the additional 25% non-viable eggs. (Not counting errors in sorting that leave gametes without a sex chromosome or with an extra, as happens on occasion.)

This would create a (roughly) 2:1 male-to-female ratio with two-father pairing and 100% female offspring (with higher success rate) for two-mother pairings.