On my 617.952, when I used to remove the oil pan bolt to drain the oil, I would replace the copper washer already on the pan bolt with the new copper washer included with the filter. I would just put the silver-colored washer into my "spares" box. Others probably know the exact reasoning for inclusion of both washers with the filter, however, if I recall correctly, it is because some engines that use the filter you mention also use one or the other of the washers - so the manufacturers have included both. Of course, this wouldn't be the first time my memory has failed me.
A couple of other suggestions for you once you've got the oil canister lid off:
1. Use a can of air to blow through the pin hole near the top of the lid on the center tube (point the center tube end into a rag). Since oil is supposed to flow through the tube, it is a good idea (I believe) to blow this clear to avoid damage if the tube were to become clogged.
2. Replace the two small rubber seal rings on the center tube. I've seen them go so long with age that when they were removed, they shattered like ceramic - not what one would typically expect from rubber. They are so inexpensive that I just replace them during each oil change - overkill I realize.