https://support.smartbear.com/testcomplete/docs/working-with/managing-projects/project-items/adding-...
If you want a separate physical copy of the test to be in another project, then copy it in file explorer from one project folder to another and then use Add Existing Item to put it in the new project.
If you just want to share a test between projects, then use Add Existing Item without making another copy. As the documentation explains, TC will show those files with an arrow icon to remind you that they are actually in another project.
