A drill bit isn't used to control center to center positioning of a pair of holes (or an array) when close tolerances are required. It is simply used to clear material out of the way in quick fashion for a more accurate method of machining. I wouldn't trust using a drill bit to maintain center to center positioning for tolerances tighter than 0.010" (.25mm) I'm not saying another machinist wouldn't TRY to drill 2 holes within that tolerance but I wouldn't. Sometimes you get lucky but it isn't worth the risk. Do it right the first time.
How critical is the exact placement of the tonearm
When mounting a tonearm how precise does one need to be?