As usual, Wikipedia has an interesting article about mayhem .

It doesn't say anything about there being different levels of mayhem, but it makes sense to me that destroying one of something you have two of is less serious than destroying both, or the only.

"Aggravated mayhem" might be something unique to California law.

Wikipedia says this about "aggravated battery":

Aggravated battery in criminal law is a more serious form of battery, and is considered a felony. Aggravated battery can be punished by a fine or more than a year in prison. Simple battery which is a misdemeanor can only be punished by less than one year in jail, or by a fine.

Acts most often defined under aggravated battery are:

•        use of a deadly weapon
•        battery in which serious bodily injury occurs, and
•        battery against a child, woman or police officer.

I don't see how Wikipedia can make a categorical statement like that, considering that any of the 50 states can define it differently, or prescribe a different punishment. This is one case where I would recommend taking Wikipedia with a grain of salt.