The memory DIMMs are neither single or dual channel, it's the motherboard that determines how the RAM is accessed. Did you match exactly the specifications of the original RAM when you upgraded?
Please follow this link to Tedster's guide for upgrading RAM: https://www.techspot.com/vb/topic47210.html
When RAM is sold as "dual channel" it simply means that there are two DIMMS (each with half the amount of the upgrade value), one for each channel of a dual channel motherboard.
almost all recent mobos are dual channel capable. Generally the slots are color coded.
Ram sellers say dual channel ready as a marketing gimmick. In reality, any ram that is certified to run on your board should also be able to run in dual channel mode when combined with an identical twin pair in a dual channel slot.