Hello,
Yes, the K66 has two ADC modules:ADC0 and ADC1, each ADC supports ping-pong mode, so two ADC modules can sample 4 channels. You can set the ADC in hardware triggering mode, you can use PDB to generate triggering signal to trigger ADC, the PDB CH0 is used to trigger ADC0, PDB CH1 is used to trigger ADC1. For more detail, you may take a look at the K66 reference manual.
https://www.nxp.com/docs/en/reference-manual/K66P144M180SF5RMV2.pdf
Also we had a useful application note "Using DMA to Emulate ADC Flexible Scan Mode on Kinetis K Series" which is more helpful for your issue:
https://www.nxp.com/docs/en/application-note/AN4590.pdf