Irenaeus, undoubtedly using Hegesippus, tells us that there were Roman bishops and gives us there names.
Eusebius writing a little over a century later (I think Irenaeus wrote around 190 CE) gives us a list of Alexandrian bishops, giving us there names.
Because Irenaeus came first, we accept his list of bishops.
Because Eusebius came second, not everyone accepts his list.
Their both likely equally bogus.
Yes Hegesippus has a list.
He also had a list of Jerusalem bishops.
No one takes that list too seriously.
No one should take the Roman list too seriously either.
But we do.
Why?
Could it be because the Roman list is "about us" and the Alexandrian list is about "others"?
I think so.