It will not be very easy to add another ImageManager tool on the toolbar, which is configured differently, please see the attached sample.
The other option to provide additional logic in the content provider seems reasonable but will also need significant amount of code. However, most probably it will be easier for your users to open one dialog, instead of two, or at least they will not have to carry about the type of images...
Let me know if I could provide additional help.
Valeri Hristov (Senior Developer, MCSD)
the Telerik team