I had the exact same thing happen in my 1996 Legacy 2.2L a few years ago. It happened while I was halfway to Portland... so I kept going and just kept adding oil as I drove. I was loosing about a liter every 150kms, got some funny looks from other drivers as I cruised along in my smoking red station wagon.
It took a few gallons of oil to get the car home. I pulled the engine and replaced all the seals accross the front of the engine, never had a problem since.
I think the reason the "old" seal has a metal surface is because it was rubbing on the backside of the timing belt drive pulley and the rubber has worn off that surface, mine looked the same.
Cool to see that I'm not the only one this has happened to!