>>I think I add the array property every time the list is loaded without checking if it already exists
I did that inadvertently with properties for years until motivated to wrap the Addproperty code in a try catch - before realizing there's no error when you add an existing property again. Have not tried with an array, though.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1