machine has both inner and outer seals, but also has an axle seal just inside the axle tube. the parts guys on quoted jobs don't usually include those seals in the job, and because the axles are heavy, the seals take a beating on r&r of axles. every truck of this type I've done brakes on, has had at least one previous brake job where the axle seals were not changed. a heel bar will get them out and the correct size socket as a drift and a hammer will install them. be careful not to hit them too hard when installing because the tube has a seat for them and you can crush them. hope this helps someone.

The outer bearings are to be lubricated grease and the inner bearings are lubricated by gear oil from the differential housing hense the 2 seals...

if you have gear oil on the shoes then both seals have gone bad and need replacing

I believe the wheel bearings are actually supposed to be packed with wheel bearing grease, not run in gear oil.
The outer seal (if I remember correctly) seals against the axle flange and prevents gear oil (from the drive axle load tube) from mixing in with the wheel bearing grease.
If you have gear oil in the bearings the outer seal has failed, or the wheel bearings have been running too loose.
The idea of using a seal to keep the axle gear oil out of the wheel bearings is not uncommon. Usually it is done with a seal situated in the inside end of the axle load tube. Hyster just has a different idea.