I noticed I am unable to create two Task Lists with the same name, however, I can create two Task Items with the same names. Why is that? Thanks
You can't create 2 tasks lists with the same name because of how the add an app form uses the limited data you provide. There is a way around it though. When you create the tasks list app, the name you give it sets the URL. After the list is created, you can rename it in the list settings to whatever you want, including a list name that already exists, although not recommended for confusion's sake.
You can create list items with the same name because the Task Name field in your list is not set to require unique values and has no exposed way to change it to be unique.