I know my brother and I both use photos with each contact, so it's easy to tell them apart from the lists.
My mother's phone shows a primary number under each contact entry, so she knows which is which.
Even if all of us would use different strategies based on names (like include our middle names, use my nickname instead of my first name, .....), that wouldn't help much when you try to match against an online service that does not keep this kind of additional information. Assume we had such online accounts (neither my father nor I have any of them, so it's a theoretical issue), we certainly wouldn't have used the name variations there that are usual within our family.
(And pls. don't shoot me now, I have little knowledge of how Hermes really works other than the descriptions found on the garage homepage. So maybe I'm really far off.)