Scratch supports remixing, taking a project and modifying it. If someone copies your project exactly, it is OK to report it, making sure to mention that it is an exact copy and posting a link to the original project.

This is especially true when no credit is given. However, if someone exactly copies your project and gives you credit, you can still report the project, as it breaks the Scratch Terms of Use.[1]

References

  1. https://scratch.mit.edu/users/Paddle2See/#comments-14825028