I think it depends more on luck as well as on your own system whether mixing brands or using no name brands will work. Sometimes, no name brands will work perfectly fine, but if you're unlucky, they may not work as expected.
Try not to mix double sided and single sided. Some motherboards just don't like it. I had one Asus P3V4X only last month that made all kinds of errors but when I removed the single sided and swapped it with a double sided from a different computer it worked again.