Here is a suggestion which I hope will help someone.
As long as all oscillators on all units are tracking the keyboard/octaves correctly, it's not nearly as big a deal if the oscillator 2 frequency isn't "exactly the same" on every unit for a given Oscillator 2 Frequency value. This is a known part of the process when trying to voice multiple mono synths to play polyphonically. Just imagine trying to do it on a bunch of Voyagers, which have nearly a dozen manually-calibrated trim pots and no auto calibration! The answer is simple and old-fashioned... tweak the knobs on each unit until the voices sound as similar to one another as you like, then save the preset on each unit once you are happy with it. By doing this, you have voiced the preset for each unit to get a more consistent result. It's a little more work, but so is playing polyphonically on a group of mono synths.
So for example, start with the same preset on each unit, stack them all so they play in unison on a single note, and fine-tune the osc2 frequency on each unit until it's exactly where you want it. It can help to designate one unit as your "master" (that you are voicing all the other units to match) and then solo the master + one other unit at a time while you make adjustments to each other unit.
Again the main point I'm trying to make is that small differences per unit are normal and to be expected, and if you want truly identical timbre on every unit it's normal to have to do a little tweaking to the preset values. The units do all need to track keyboard and octave similarly, which they should do... but if a small change to osc frequency or waveform is needed, just make the adjustment and re-save the preset once it's tweaked to your liking.
Cheers,
Amos
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