Hi there.
If it is a Dubl Duck in good condition, I would advise against using it for honing practise. DD's are fairly expensive (depending on condition of course) and you don't wat to ruin a 100$ blade on your first attempt.
If you want to learn honing a better option would be to buy one or two blades on ebay to practise on.

As long as the razors are from solingen steel or sheffield steel you have a quality razor. The blades don't have to look nice as long as they are not too damaged to actually hone them.