I tried this. The name of the new project was good, but with the menu of the old one.
I decided to delete old version for 1.5 and 2.5. No more need of this.
Now I think I have the good url ID of the Project :
www.j-cook.pro/sandbox/cms30/administrat...?option=com_demo9949.
But in Component / J! Breeding , the url link is always the old one com_demo693 ... and sub-menu are not updated too ...
So many SQL error ... or component not found ....
Let me know what can I do more ... Big bag node, I think !!