Duraluminum is an outdated marketing term for.....wait for it.........aluminum. I worked in the cycling manufacturing industry years back and learned a few things about aluminum pedigree.
Wrong.
Duraluminum is an ALLOY of aluminium, copper, manganese, magnesium, iron and silicon. It is NOT aluminium.
Duraluminum is lighter but harder than steel, its mechanical properties are quite different to aluminium.
I hope the other things you learnt during your employment in the cycling manufacturing industry were founded on fact.