The usual tech term for dual phase is "two phase" which is derived from two totally separate power sources (i.e. two transformers, two generators etc.) ...no intermingling of the two power sources. This setup is common in industrial heavy demand load like 50-100 horsepower motors. Crushers for cement aggregate plants for example. Steel forging plants with those heavy hammers.
The term "two phase" is used for a system where the phases are 90 degrees apart, produced by a single generator.
https://en.wikipedia.org/wiki/Two-phase_electric_power