Here is the info on Crankshaft head seal installation out of my J/E 1989 9.9-30 manual . With the seals facing each other,it serves as a little grease reservoir for the 3 cc of Triple Guard grease as recommended ,before lower unit installation

As i recall from my Metric System "research", a cc and a ml are the same amount. So 3 cc’s isn’t much grease to place in the space between the seals, more may prevent the driveshaft splines from seating fully.
This newer 2 seal design seems like an improvement over the earlier single seal and driveshaft O Ring design.