Though.., yet..
- Though he might not have recognized me, yet it is rude of him.
- Though he is my relation, I shall not spare him.

If I put yet in the second sentence, will it make any difference?
And what if I don't put yet in the first sentence?

Question

Though.., yet..
- Though he might not have recognized me, yet it is rude of him. 
- Though he is my relation, I shall not spare him.

If I put yet in the second sentence, will it make any difference?
And what if I don't put yet in the first sentence?

Answer

The language is not contemporary. As you suggest, "yet" could be omitted in the first sentence, and added in the second sentence. Personally, I would be inclined to use "still" instead of "yet."