[Nogbad]

since 2 preparations would be more likely than 3

Not necessarily.
The Donor may have wished
to experiment
with various types of anthrax
in a 'real-life' situation
just as the European countries
tested their weapons
supplying them to both sides
in the Spanish Civil war.

[Mitchell]

I was rethinking this just as I got your message; there may, in fact, be a difference between FL and NY anthrax.

The FL anthrax caused two cases of inhalation anthrax, but no cases of cutaneous anthrax. The NY anthrax caused cutaneous anthrax but no cases of inhalation anthrax, at least in the target buildings. (We don't know if Kathy Nguyen, Ottilie Lundgren, and the postal workers were infected by the NY anthrax or the DC anthrax; I would guess cross-contamination with the DC strain.)

This suggests that the FL and NY anthrax had different physical characteristics from one another (and/or were delivered differently -- we don't even know if there was a letter in FL, after all).

I don't think that different strains would explain this -- as far as I know, the strain has nothing to do with cutaneous vs. inhalation anthrax; any differential would be based on physical characteristics and delivery methods, as I understand it.