Hardware Secrets has posted an article about the Intel Dual Core Technology

ntel has also recently announced its dual-core technology for their processors. Two new CPUs for the desktop market were announced: Pentium D, which is the dual-core version of Pentium 4, and Pentium Extreme Edition, which is the dual-core version of Pentium 4 Extreme Edition. As you can see, the dual-core processors aren't called "Pentium 4" as one should expect.

Read more