CPU-Z tells you if soldered RAM is dual-channel.

Open CPU-Z, go to the Memory tab, and look at “Channels #”. If it says “Dual”, you’re good. If “Single”, it’s single-channel. That’s it.

The motherboard layout can give you a hint — two physical RAM chips on the board likely means dual-channel — but CPU-Z is definitive. Soldered RAM is still just RAM; the channel configuration depends on how the manufacturer wired it.

Don’t trust the laptop’s spec sheet blindly. Lots of cheap laptops solder a single module to save money. CPU-Z doesn’t lie.