If you create a second pipeline job against the same github repository, Jenkins will detect that there is a naming conflict and prompt you to enter a unique name. However, it's not possible to enter any text into the input box.

Jenkins 2.107.1.1

Blue Ocean plugin: 1.4.2

Steps to reproduce:

1. Create a new Pipeline
2. Select Github
3. Select an organisation
4. Select a repository
5. Create the pipeline
6. Create a second pipeline
7. Select Github
8. Select the same organisation as in step 3
9. Select the same repository as in step 4
10. Jenkins detects the naming conflict and prompts for a unique name, but you cannot enter anything into the text box