Running dual channel depends on your motherboard - not necessarily the RAM modules.
- If it is a dual channel board, then you simply install the RAM modules in the slots as per your motherboard manual and it will run dual channel.
- Also word of warning, mixing RAM modules is not guaranteed compatibility, so there is no guarantee your new module will work with the old.
For example, a dual channel architecture motherboard, with 4 RAM slots, will have 2 slots dedicated to each channel. You just have to install the RAM in the corresponding channels (your motherboard manual will tell you which RAM slots to use first).