For what it's worth, if anything... you can make a copy of a dynamic block and rename it on-the-fly. Given code posted elsewhere by Tony called CloneBlock. It uses an ObjectDBX file to create an exact duplicate of source block name. Then it copies the renamed block back to the active document.
AFAIK, this is the only way to clone a dynamic block. Other methods which attempt to clone a block using entmake within the active file, will fail to bring a dynamic block's info along.
Tony's function is an example of how to do it. It needs a wrapper for cosmetic and error handling reasons. I'll post my wrapper if ayone is interested.