Are there discounts on additional single point-to-point train tickets?

I will be traveling in Spain soon and plan to purchase a rail pass. Let's say, for instance, that I buy a 3-day pass but it turns out I need four days. Is there any sort of discount for the additional ticket because I have already purchased a rail pass for that covers the days my rail pass is good?

I hope I have formed this question so it makes sense. I can't think of a better way to say it.
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