From looking at the nameplate in the attach image, I suspect the motor does have two field coils: first field coil is connected between J1 and K1, second field coil is connected between J2 and K2. The two field coils are probably identical, as each line on the nameplate shows the same current in both field coils.Note that the nameplate shows two operating speeds, with different field-coil currents. The no-mechanical-load speed of a DC motor is the speed at which the motor, used as a generator, would generate a voltage equal to the voltage applied to the motor's armature commutator. Note that the higher-speed rating line on the nameplate specifies lower field-coil currents than does the lower-speed rating line on the nameplate. For more details, look up "shunt-field DC electric motor" or similar phrasing. Look up U.S. makers of large DC electric motors: Their datasheets will be in English, and the terminology will be the same as is on the nameplate.
I notice that the top right corner of the nameplate mentions Brown Boveri. Maybe they marketed the motor?
