It is NOT necessary to install multiples of RAM in any format
Cypherus, I think that you will find that what Bushfiva has written is absolutely correct. It may not be as common now as it once was, but it most certainly was necessary to install RAM in matched pairs in certain systems.
You are right that the specs for the RAM should be checked with the mobo manfr's website. Failure to do so can result in a non-working computer, or one unnecessarily crippled by running at the speed of the slowest module.
SD