Hi, not sure this can actually help you, but I’m getting your exact results from the DVD iso image itself (not burned to physical media) as downloaded a few days ago via bit torrent and the “Check Media” option on the installer passes without complaints.
So apparently nothing wrong on your system, maybe the CHECKSUMS master is plainly not up to date; please note that I’m just a common user (lke you?), so maybe those in control of the images might have a different view.
Those seem correct, based on comparing the first few and last few digits of the sha256sums.
The point, though, is that “isolinux.bin” is what boots the installer on a non-uefi system. So that file is modified at the final step of preparing the iso, which will be after the CHECKSUMS are computed.
I’m pretty sure we (forum readers) have had this same discussion before – perhaps for the Leap 15.0 installer.
Honestly just verify the iso itself. That is sufficient.
For the record, to check your numbers I used the command:
mount -o ro openSUSE-Leap-15.1-DVD-x86_64.iso /mnt
This mounts the iso (a loop mount), where I can look at the files and check their content (as in computing the sha256 checksum of that one file). But if you try this, it is important to mount “ro” (read-only). Otherwise the iso itself may be modified and no longer match the published checksum for the iso.