- Churchill was a great orator and a great politician of his times.
- Churchill was a great orator and politician of his times.
Both of the above sentences are not only correct but also mean exactly the same thing.
But the following sentences have different shades of meaning:
- Tagore is a great poet, painter, singer, dramatist, novelist and patriot.
- Tagore is a great poet, a painter, a singer, a dramatist, a novelist and a patriot.
Both the sentences are grammatically correct.
The first sentence emphatically says that Tagore is great in all those aspects.
The second sentence may mean that Tagore is great as a poet but just a painter, singer, novelist and painter. The greatness of Tagore may not be implied to his other qualities.
So if we want to say that Tagore is great in all aspects the sentence 1 is preferrable.
I would like to give another example which shows how the omission of the article brings a change in meaning:
- A black and a white cow are grazing (two cows having different colours).
- A black and white cow is grazing (a single cow having both colours).
I will provide the link which explains the topic
My answer is based on the books I have read and comments on the site and my research on the internet.