Multiple listings for the same brand and type of part merely indicate different suppliers. Unless otherwise noted, they are the same part.
Shaft Sealing Ring for Porsche
Shaft sealing ring for the crankshaft to the flywheel side.
"Shaft Seal 85x105x11 996/997/986/987/987c, 955s/t, 957s/t/ts/gts, 958s/t, 970"
Corteco Crankshaft Seal for Porsche
Reinz Crankshaft Seal for Porsche