You got eagle eyes !
But I guess the names are because the following lines (sub-projects) belong to a "different class" of sub-projects.
Note the very first entry (at the top of the page) contains "LLR".
LLR/LLR2 sub-projects are then listed.
Then, somewhere in the middle you find "Generalized Fermat Prime Search".
And you have GFN sub-projects listed.
"AP26 / AP27" is the only sub-project in the "Arithmetic Progressions" class.
The same for "Wieferich and Wall-Sun-Sun Prime Search" in the "Wieferich and Wall-Sun-Sun" class.
Maybe a larger spacing between these "classes" would make it more clear.
"Accidit in puncto, quod non contingit in anno."
Something that does not occur in a year may, perchance, happen in a moment.