In this command example add n/hubert s/Geography s/Geography p/98765432 ........
The repetition of s/Geography is most likely accidental. In this case, the input is not ambiguous, because the subject is clearly Geography. Not accepting this input means the user need to do additional step of deleting the repetition.
Suggestion: If the user accidentally retype the same field but the values are the same, the developer can just accept the input as it is not ambiguous.

In this command example
add n/hubert s/Geography s/Geography p/98765432 ........The repetition of
s/Geographyis most likely accidental. In this case, the input is not ambiguous, because the subject is clearly Geography. Not accepting this input means the user need to do additional step of deleting the repetition.Suggestion: If the user accidentally retype the same field but the values are the same, the developer can just accept the input as it is not ambiguous.