Why this error comes?
1. column with same name is already created
2. or it is reserved.
it might be possible you create a column with name 'abc' then you delete it and again try to crate column with name 'abc' and it gives error
At such situation you can use below method:-
1. open create new column page
in address bar.
3. hit enter
now you will be able to create column with name 'abc'