"Dual Channel" and "Tri Channel" refer to the memory controller in your system, not to the memory itself. A "Dual Channel" system can access two DIMM modules at the same time, while a "Tri Channel" system can access three of them. The DIMM modules themselves are identical.
You can buy "dual channel kits" or "tri channel kits" of memory, but it's just the same memory packaged in pairs or triplets to optimize the number of DIMM modules you install into a dual- or tri-channel system.