The astute investor reads the prospectii carefully.
Consulting the prospectus for FMCKJ reveals the interesting distinction that at least some Freddie preferreds have a par value of $1.00. I believe the par on FNMAS may be $0.01 but as I don't own it I never read that one specifically.
Again, these discrepancies are a reflection of the payoff hierarchy- the prefs are paid before common in the event of receivership.