Is the fixed spray zone a fill in zone? Meaning, it fills/covers an area the other zone couldn't fill completely.
It's normal to have a fill in zone. The precipitation rates will be different for sprays and rotors. Sometimes the characteristics of the zone are different too, e.g., shade, slope, structure.
Do you think you need both zones running? If so, then you will have to fine tune these zone run times to not over water.