The only thing you need to do to clone an existing shape and directly set a custom position is hold down the Ctrl key (which is Cmd on the Mac) while dragging a connector from one of the connection points or arrows.
View our playlist on shortcuts: https://drawio.link/shortcuts
See all of our shortcuts here: https://drawio.link/shortcutlist
Get your 30-day trial – draw.io is available on the Atlassian Marketplace (https://drawio.link/marketplace)
Or learn more about diagramming with draw.io at https://drawio-app.com/learning. You can also take a look at our blog (https://drawio-app.com/blog) to always stay up-to-date on new draw.io features in Confluence.