Cannot create site with the same URL as an already-existing site

[CMDJojo]

I cannot create another site with the same URL as an already-existing site. It would be cool if you could do that, so you could clone one site to make another edition of an existing site. However, if this is intentional, it should at least give a warning or a message (I get no warnings nor messages, it just says "Creating site" for a couple of seconds and then it disappears)