what happens if I upload a changeset with the same fields as the target system?
It validated fine but just curious to see what happens...
Does it update the create date?
If target system component and source system component are same then there will not be any difference in audit fields (Created/Lastmodified etc.)
Same means, there is no configuration level difference.
These fields change only if there is difference in configuration.
Note: Created date never changes except the sandbox refresh.
createdDate
won't be updated, but theLastModifiedDate
might.