Main screen: what happens if a user accidentally names their new model the same name as an existing one?

### Scenario

User chooses "Start a new model" option and names their new model "Model-1"; however, a "Model-1" has already been previously created.

### What currently happens
--- need to test to find out

### What should happen
- Option 1: the new directory will overwrite the existing directory, with a warning to user
- Option 2: warning to user the name has been used, so they can choose a different name
- Option 3: combine both Option 1 & 2: warn user when a same name has been used before, but allow them to overwrite if needed

### To ponder
Currently users have to check the existing models drop down in order to see what's there, and it's only showing the model (directory) name and not its content, sometimes it might be hard to judge if a folder is worth keeping or not. Maybe a better model management feature in the future might alleviate this issue.