Just thinking if they were 4-wire with no info as to what the wire colours were, then wiring to one colour scheme (when it was another) could easily have got it wrong. Even if you belled-out the wires to ascertain the two coils, you'd still have to empirically test the pickup connections in order to guarantee a full humbucker sound.

The quoted Henries values for the Belcats seem about right for similar humbuckers. Maybe they cheated and only put one bar magnet inside instead of two? You always have the option of fitting a kit pickup in to see if there's a marked difference in output and tone.