The T4500 is called Dual Core as it's from Intel's low end CPU line
The T4400 is called Core 2 Duo as it's from the Core2 line of CPU's.
The spec's are very close, if the T4400 was released today it would be called at Dual Core.
Intel also hosts live chat event with their experts where people can discuss Intel products technologies and get instant answers to their questions. The next event will be held around their core processors and I think that it will be a good platform to ask such questions. The next event is on 26th March at 9:30 am GMT. More info at