Mike,
I guess we are going to need to "agree to disagree" here. I would be interested in hearing what safety you are adding by requiring an additional receptacle. You are not going to eliminate the use of an extension cord, because the code allows the receptacle to be a maximum of 25 feet from the equipment. You are not going to eliminate overload as we all agree that this receptacle is allowed to be on the same circuit as the other outdoor receptacles. So, other than being obstinate, what is accomplished by requiring the third receptacle? The whole point of duplex versus a single receptacle just makes no sense at all. An outlet is an outlet. The code says that I must install an outlet within 25 feet of the equipment, it also says that there must be at least one receptacle on the front and one receptacle on the rear of a single family dwelling, I can find no justification for not allowing one of these receptacles to also satisfy the requirement for the HVAC receptacle. The code says what it says, and it does not say that the HVAC receptacle has to be dedicated to the equipment, on a seperate circuit, or anything else. It just says that there has to be a receptacle within 25 feet of the equipment and that it must remain "hot" even if the disconnect for the equpment is open.