It is allowed whether old or brand new, no hassle.

As per the Nepal custom site. One passenger can take one (Laptop or Ipad or tablet.) That means you can take one of these three items per passenger. Otherwise, they will make you pay tax on the additional items.
Also, As per Nepal Custom site. You are allowed only one phone per passenger. Additional phones are charged additional taxes or fees.

Having that said, During my last two visits., in one visit, they opened my luggage manually and check for the Extra phone and gave me really hard time for having the extra phone.

Second visit. there was no one to check if I had an extra phone or laptop with me. Basically no one checked at all.

Also, With my recent travel with Etihad, now they do not allow you to carry any device with a Lithium battery. Apple product contain lithium batteries. like iPhone, Ipad. MacBook. Please check on any device that contains lithium batteries.