deleted Data Extension still causing "duplicate key value" error for creating DE with same name

Question

Using the Python FuelSDK, I created a Data Extension. I then used the dashboard to delete it, and I saw it successfully delete.

Upon again creating a Data Extension with the same name, I received this error:
"Error occurred while saving Custom Object <My Data Extension Name> (00000000-0000-0000-0000-000000000000): Cannot insert duplicate key row in object 'dbo.CustomObject' with unique index 'IX_CustomObject_MemberID_CustomerKey_uncl'. The duplicate key value is (<Some Number>, <My Data Extension Name>)."

Is this perhaps because of Exacttarget still having the original Data Extension cached, and soon I will be able to again create a Data Extension with that name?

Or is this name in fact never usable again?

(Name and CustomerKey have the same value in this case, so I'm saying "name" in the above question but note that I'm also talking about "CustomerKey".)

Answer 1

Previously, when deleting a data extension, the Marketing Cloud would slightly modify the name and make the data extension "inactive" on the database. What it did not do, is modify the External (customer) Key. This is no longer the case and both the name and external key are updated when a data extension is deleted so it may be reused; however, if a data extension folder is deleted, the data extensions in that folder is essentially hidden and you will not be able to create a DE with the same name/external key.