Am I being unreasonable and spoilt?

I realise this is the question of a very spoilt girl.
Some months ago, when I graduated college, I was awarded a minor scholarship by my school for excelling in a subject. My mother feels like my sister (we're twins) also deserved the scholarship, and that may be true, seeing that she seemed to have a fairly unattentive/disinterested teacher, but only one person could be given the award and it turned out to be me. Now, my mum decides that in order to show my sister that she and my dad think she deserves recognition as well, she will give her a tablet of her (my sister's) choice, even though my sister, good as she may be, on numerous occasions has "boasted" abt how little time she has spent on her school work. I already have a tablet, I got it for christmas/my birthday (our birthday is on christmas eve) bc of the difference in how much they have spent on her vs me during the last few years (a fairly large sum). My mum says I should be happy knowing they would have given me what they gave my sis, if they could have (I quit my riding lessons while she continued bc I was afraid, and I got sore eyes/blurred vision from wearing contact lenses, we both need an expensive prescription type) and my dad thinks I'm ungrateful counting everything I haven't got, but I can't help feeling a bit upset. Why would the "feeling" that if they had their way, I would have got everything my sis got be enough, while my sis is given a tablet to make up for the school's decision they found faulty?

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