He did read your question (or I misread it as well). most modern motherboards come with 4 slots, 2 slots per channel. for best results, keep the two sticks channel isolated to keep potential problems a minimum. while the memory sticks may talk at the same speed, and talk the same to the memory controller, they might not like talking to each other.
even if they are the same speed, the latencies might not match either, and you will be going with the slowest of them.
For best results depending on your system, if you have the 2 memory channels, get a seocnd stick from each company that matches. you will get better performance and better compatability.
If not, then it still might work, but it isnt 100% that you wont have problems...