The first images have a valid FAT12 bootsector. The second set of images does not, looks like there was some kind of custom T&E boot sector.
(If you open the images with FIVEC, the ones with a valid FAT12 boot sector display some information, and the FAT12 tag is added to the right-hand side. That does not occur for the custom boot sector image.)
Amusingly enough, the next sector 0/0/2, did contain a standard FAT table. So I lopped the boot sector off the other disk and stapled it onto the one you can't read.
You should be able to dump this with DiskExplorer ("Plain Image") now, I think:
http://www.pc98.org/temp/091921.rar