Yeah, I did the same thing before because of what the manual says, but it wouldn't run in dual channel. Now I put one in first green and other in first purple and it runs in dual channel.
if ur wondering if thers a differnt between running ram in single channel or dual channel.. well you shoudl see a performance increase if you switch to dual channel... it also depends on ur computers mood because ive seen some ppl get a very small amound of performance increase and others performance goes up considerably