We can also go by the fact that Apple has used single 1 GB chips in the past, including in the iPhone 6, and there doesn't seem to be any reason for them to suddenly switch to two 512 GB chips 😀
Also it would be strange for the benchmarks to get it wrong when they're obviously reading system values (as opposed to software that sometimes comes out after a device is released that just looks up the device type and makes a hard coded assumption based on that).
Right. You assume, but you didn't get that informati from this teardown. All we have is a part number and 2 chips. Then we can deduce what this means.
This post seems to say that ifixit confirmed it was 2GB which isn't true.