Numbers are Being Added to My SharePoint List Internal Names

When you create a list or library, the name you enter becomes both the internal name (used in the url), and the display name. When you rename a list, only the display name is changed. If you later create a new list with the same name as a renamed list’s original name, the new list’s internal name will have a number added.

Here are the steps to show what's happening:

1. Create a new Custom list and name it "TestList".
2. Navigate to the list and note that the URL contains "TestList".
3. Go to the list and List Settings and use "List name, description and navigation" to rename it to something like "TestListNorth".
4. Note the URL. It's still "TestList".
5. Create a new Custom list and name it "TestList".
6. Navigate to the list and note that the URL contains "TestList1". This is also the internal name. The display name is "TestList".
7. Change the display name of this list to "TestListEast" and note that the URL is still "TestList1".
8. Create yet another new Custom list and name it "TestList".
9. Navigate to the list and note that the URL contains "TestList2". This is also the internal name. The display name is "TestList".
10. Change the display name of this list to "TestListWest" and note that the URL is still "TestList2".

The internal name is both unique and not changeable from the browser user interface. The display name is also unique amongst the display names, but can be different than the internal name.

Keep in mind that the deletion of large objects in SharePoint is a gradual and background process. You might get numbers added to the internal name when you delete a large list, or even a Site or Site Collection, and then recreate those objects and lists using the same names.