incorrect to use the pronoun with "a" on its own without the second short pronoun

Question

In the quiz, the statement was supposed to be correct: El director entregó un premio a los estudiantes.

However, the explanation seems to contradict that. Can you explain why?

It would be incorrect to use the pronoun with "a" on its own without the second short pronoun:

A mí diste muy poco dinero pero a ella diste mucho.¿A tí regalaron tus padres una moto el año pasado?

Accepted Answer

Hola Alejandro
It is when we place the indirect object right in the beginning of the sentence, i.e.:
A los estudiantes el director les entregó un premio.
In this case, as we've placed the indirect object with "a" in the beginning, we cannot omit the short pronoun.
This would be incorrect:
A los estudiantes el director entregó un premio.
But if you change the order as we did:
El director entregó un premio a los estudiantes. 
As we have the "a" indirect object at the end, we don't need to repeat with another pronoun.
I hope this clarified it.
Saludos
Inma