In the process of bulk uploading, the unit types get created when the system detects that you provided the same information, such as Unit Amount.
For example, For One unit, the Rent amount is $1200.00 and the second unit is also amounting to $1200.00
This signals to the system that you are providing the same information and just creating another type of unit.
Note: The system automatically creates unit type based on the number of bedrooms, Bathrooms, Rent and SqFt.