If they are both yours and they don’t want one of them for any justifiable reason, you are not obliged to obey them as there is no interest in it for them. However, you should be diplomatic in dealing with them.

I have two phones, the old one I use to listen to quran and the new one to do other things. Do I have to obey my parents if they tell me to use one of them only? I know it’s important to obey parents but, what should I do in this situation?

Etiquette, Morals and Heart-Softeners | January 16, 2015 3:29 pm
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Is it permissible to write a reference note on the side of the Quranic ayat . If I am reading an ayah and for my better understanding can I write in Quran on it’s page it’s meaning so that whenever I am reading I will understand what does it means ? Or Am I sinning by write next to the ayah ? 
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 IS it permissible for me to play chess on my phone? The horse’s head will still be there as well as the cross on the King piece’s head but it will be virtual.