Thank you. It seems that having quoted that there are two types of entities. Davey now seems to be informing us that there is no difference between them. That which he quotes clearly gives the distinction.
The difference is the context.
You cannot say that an entity is necessary or not without also stating what it is necessary for - in other words the context.
So use the child/parent example (the context). If I exist then my father cannot fail to exist and therefore my father is a necessary entity. If I do not exist then my father can exist or not, so is a contingent entity.
If we change the context and talk about the existence of the universe - my father is not necessary for the universe to exist, so my father could exist or could not exist in the context of the existence of the universe. My father is a contingent entity in that context.
In each case the characteristics of my father are identical, but depending on the context my father may be a necessary entity or a contingent one.
It isn't rocket science.
And while we are on the parent/child context lets nail your nonsense that there can only be one necessary entity. Clearly is I exist then my father is a necessary entity, but if I exist then my mother is a necessary entity too. And if I exist a functioning uterus is a necessary entity as are a whole range of other entities, e.g. oxygen, water etc etc. There are many necessary entities if I exist.
