Dual RX enables dual reception on two different bands. Years after the first MF was above the bands, manufacturers rediscovered the benefits of a lower intermediate frequency. In TS-990 it is 8.248MHz. Five roofing filters from 270Hz to 15kHz are supplied as standard. IP3 is +40dBm (without further refinements). Triple takes care of further filtering DSP. The oscillator, which according to its purpose is a VCO/DDS or PLL, is quite complicated.
There are two TFT displays for displaying data. By using two displays, the manufacturer is trying to facilitate accurate tuning or better orientation when split operation.
Full information about the TS-990: http://www2.jvckenwood.com/en/news/2013/20130108.html