This dashboard control (in the settings section) allows you to copy property values to a different property on the same document. Documents can be selected by their document type.
This is especially useful if you need to copy/move already existing document data from one datatype to another; i.e. from a simple 'Textstring' to the 'Dictionary Datatype' for multilingual values. If you (optionally) supply a text pattern string, the source value can be embedded in XML for instance or data can be appended or prepended.
You can also easily duplicate fields to let editors work on them (but not outputting to the website) just in the backend and copy the update date back to the originating property at a specified date or event -- and publish after copy if needed.
Version 1.0 of the package is only compatible with Umbraco version 6.1+
Version 1.0.1 is compatible (tested) with Umbraco version 4.9, 4.10, 4.11 and 6.1+