You may easily copy collections from one collection type to another, for example a collection in the stock library may be copied to become a collection in Events and Galleries.
Enter the collection you wish to copy, (Control Panel -> My Images, then click on the collection name). In the collection toolbar, click "Move or Copy". Then click "Copy Collection" , and click "Next". Select the location that you want to copy the collection to from the drop down list of all your collections, and click "Copy Collection". Leave the browser window open until the process has completed.
File count restrictions may apply to certain account types.