I have 2 first cousin matches on 23andme.. both named ‘John’. Their relationship is listed as grandson/grandfather. With that age difference and relationship they both cannot be my cousin. I’m adopted and had a great life this just has me stumped .. like a word problem from HS. Both 19 segments and 10.8% and 7.43%...
It's often difficult to ascertain relationships precisely from individual pair-wise matches (or even from 2 of them), in the absence of family tree knowledge. From the DNA Painter Shared CM tool, one relationship that fits the numbers is if the "grandfather" is your great-grandfather, and the "grandson" your first cousin once removed (1C1R). But, I suspect that doesn't fit the actual scenario.
It's also possible that there's some other factor that causes 23AndMe to infer the grandparent/grandchild relationship for these two persons, when they may actually be, e.g. uncle/nephew (they look very similar from numbers alone).
Best bet - contact these two members, explain your situation, and find out how they're actually related (better than trying to guess from match numbers).