It is not clear what you are asking. You can set whichever drive you wish as boot drive in bios. The old disk 0 conventions died out years ago.
Agree. Anyway... From the OP's post... (and the fact that I do have two near identical NVMe (Samsung 970 Pro (512 & 1 TB)....
My motherboard has two NVME M.2 slots. If both slots have WD SN750 2TB installed, which slot will I use when I install to Disk 0?
In this case disk "0" will be the first capable boot disk. And though it may say disk 0 on the install screen, as noted elsewhere, disk numbering will change once the OS loads. Example when I disable my SATA drives my NVME drives become disk 0 & 1. Once I re-enable the drives after the OS install, my NVMe drives revert to disk 3 & 4, and my SATA disks become 0, 1, & 2.
Now where you have multiple drives in the system, you can usually tell which is which by name, size, or usage. If the drives were used prior to a new OS and never wiped, you'll usually see "C" next to the current OS drive. Choose the drive you want, install the OS, and that's the boot drive (regardless of "disk numbering" and being identical drives) the system will boot from - unless you have an OS on both drives, then things can get a little complicated.
However, if you're only booting from one OS drive, there's no drive confusion.
Is there a 50/50 chance that it will use either the top or bottom slot each time I boot the Windows 11 installer and choose Disk 0? Having two identical drives can easily cause a confusion.
No. As mentioned above, the drive with the OS & boot files will always be the booted drive (unless the boot files become damaged).
That's the simple. But yes, one can always deep dive with what ifs and maybe so's, but simple works 99.999 percent of time :)
Now If the OP is looking for something a bit more elaborate, it's not in their original post(s).
