Two 8GB sticks usually run dual-channel.

Yes, as long as you put them in the right slots (typically slots 2 and 4, or 1 and 3 — check your motherboard manual).

Two sticks of the same capacity will almost always enable dual-channel mode. That’s the whole point — dual-channel needs matched sizes. Speed and timings don’t have to match exactly, but the system will run both sticks at the slowest stick’s speed. So if your old stick is 2666MHz and the new one is 3200MHz, they’ll both run at 2666MHz.

One catch: if your motherboard is very old or cheap, it might not support “flex mode” for mismatched ranks (single vs dual rank). But for two 8GB sticks, that’s rarely a problem. The bigger risk is buying a stick with different voltage or incompatible memory type (DDR3 vs DDR4 vs DDR5 — don’t mix generations).

Just make sure you put them in the correct slots and you’re good.