Combine the peaches, cherries, lemon juice and pectin in a large pan. Bring to a boil. Add sugar and a dollop of butter to take care of the foam. Stir constantly and bring to a boil again (a hard boil that cannot be stirred down). Stir and boil for one (1) minute. Remove from fire and stir for several minutes. Fill hot jelly jars (7-8 cups jelly) and top with hot lids and rings. Put in a hot water bath for 10 minutes. This is not only delicious, but looks very pretty. I think you could also make this at the holiday time by buying frozen peaches if you don't have some in your freezer.