All GeForce2 Pro cards come with DDR SDRAM. If it has SDR memory then it is most definitely not a GeForce2 Pro.
DDR SDRAM has double the peak theoretical memory bandwidth of SDR SDRAM at the same clockspeed and bus width. Performance differences can vary depending upon the actual configuration, in some cases DDR SDRAM can actually be slower then SDR SDRAM, and in others it can be vastly superior depending upon the need for extra bandwidth against the lesser effeciency of DDR, memory bus width, clockspeed etc.