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The major feature of M1917 production was that, as far as possible, all parts from 3 different manufacturers should be interchangeable. So no US armourer fixing up M1917s would have worried much about matching E's or R's or W's. Part interchangeablilty was intended to be used to produce as many rifles as possible as fast as possible in the factory, and to keep up the maximum availability of functioning rifles in the field. Especially for the M1917, the snooty collector's attitude of "it's not all matching therefore not original" is historically incorrect. See Ferris "United States Rifle Model of 1917".
As to "history", nobody can tell now whether the parts were used in the factory, because delivery shortages required taking parts from one of the other factories, or "officially" swapped by a US armorer at a later date, or even swapped by you or me five minutes ago.
So go all-Eddy if you like. It's irrelevant for shooting anyway