The way clans are structured is this: clans have members. Think about that for a second. It's not that your account is a member of a clan, it's the other way round.
The clan, as an entity, knows who is a part of it. These are unique records, as in, only one clan can "own" an account. You are either on that clan's membership list, in which case your xp is recorded, or you're not, in which case your record is wiped.
Hope that goes some way to explaining.
Mod Maz
Queen of the Squirrels
RS Training & Developer Lead
16-May-2017 07:54:51