I would say the same thing. Try and take them at least 50 yards away from each other to help prevent the echo from happening. I had the same thing happen with mine. At first I was irritated, hoping that I didn't buy something that would cause me problems. However after increasing the distance ...

Check out the manufacturers website. I have found that most of the manuals are available for download these days. Makes it easier for those of us that don't always keep those things around. I can't imagine how cluttered my space would be if I had every manual for every gadget I own.