Hello,
I tried to change an object name to Circle.10.001 but it changes to the default Circle.001. Circle.9 changed without problems.
Thank you
You probably allready have an object in your file named Circle.10.001 so it is automatically renamed to next free Circle.xxx name. It is not possible to have two objects with the same name in one file. Object names have to be unique.
Note that it is not necessary that the object is inside your scene. It might as well just be saved in the blend file. So if you do not see the object in the outliner you can switch your outliner to “blend file” mode in the drop down menu and check there under “objects”.