The 89c51RD2 available from Atmel and from Philips are not the same in terms of the built in peripherals, eram, ISP software and the bootloader.

It is not true that the ATMEL 89c51RD2 is not available in DIP. I remember to have seen it. Maybe you can search for T89c51RD2.

To ISP the Philips variant you need the FlashMagic software from www.esacademy.com.

For the ATMEL variant you need FLIP from them.

Anyway both are free downloads

Raghu