I received this from Jeff at Steve's. I have not had an opportunity to trace the wires but thought I would post for future reference.
The RSM650 uses the PARMAX2 Extreme boards, those hold 14 LEDs, with every alternating LED on it's respective channel, so 2 channels total per PARMAX2. You'll find that there are 4 wires coming off each PARMAX2, with the top pair being one channel, and the bottom pair being another channel. That said, each pair will be going to a different driver. If you are able to trace each wire pair, they should be go separate drivers, if they are going to the same driver, that would be the problem.
The wiring should be like this.
Channel 1 - heatsink #1 - all 4 PARMAX2 boards white LEDs only
Channel 2 - heatsink #1 - all 4 PARMAX2 boards blue LEDs only
Channel 3 - heatsink #2 - all 4 PARMAX2 boards white LEDs only
Channel 4 - heatsink #2 - all 4 PARMAX2 boards blue LEDs only
Remember that the color of LED they dim is irreverent and may be the opposite, however, each channel should be dimming all the blues or all of the whites on a single heatsink.