I have come across these spacers in two different thicknesses...One or the other will be required whichever wheel bearings you use...
It seems that bearings of different widths must have been used at various times but I have no idea when.
When the thicker of the two spacers are used in conjunction with what must have been the wider bearings there is insufficient thread remaining exposed on the bearing carrier tube to fit the bearing adjustment lock nut...
If you have this combination of parts it will be obvious when you assemble the hub...However, leaving the spacers out is too much of an 'adjustment'...The thinner spacers will be needed...
Sorry I can't be more definitive with dimensions but I always use the same type of bearing and build up new hubs so rarely, that in the past I have made adjustments to suit as required on a case by case basis...
..Ian
email (option): ian@wright52.plus.com