I need help copying a version of a photo which is in a project to another project so it is in both projects. 

Each year we make Christmas ornaments from photos taken over the years. Every year up to now I would make a new project folder called Christmas ornaments 20XX and then go to all projects created during the year and drag a version of the photos I wanted into the new project. The original and the versions would remain in the original project folder and a version would be added to  the new Christmas ornament folder. Now, if I drag a photo to the new folder, the original and the version move to the new project leaving nothing in the original project folder. 

Something has changed and I don’t know how to accomplish my task. Can someone point out my error? All help appreciated.