I'm coming across an issue when trying to use item types. The DC metadata will appear under the DC Metadata Area, and then repeat again in the custom item type. For example, Title will appear under both headings.
Any ideas on how to get fix this so it only displays the fields once, preferably as item type metadata?
Have you (somehow) added Title to your custom item type?
Title and other Dublin Core metadata elements aren't meant to be used in item types, and it should be impossible to pick Title when adding an element to a type.
I did put Title and quite a few of the other DC elements into item types. It allowed me to add all of the DC Metadata into the custom item type.
Regardless of whether the type form allowed you to add those elements, there's really no point in adding elements from the Element Sets to an Item Type.
Elements that are part of a Set are automatically available for every item of every type.
Removing Title (and any other DC elements) from the Item Types should get rid of this double printing of the metadata.
Upgrading Omeka should resolve the problem where you can select the Dublin Core elements in the first place.