Goods for personal use transferred across the customs border with exemption from payment of customs duties:
2.14. portable personal computers (laptops) - no more than 1 item
(c) http://www.domodedovo.ru/en/main/infopass/6/1/
For instance, if you bring in a laptop, you don't need to declare it and no tax should be paid, even if you know it costs more than $2150 US. However, if you bring in two laptops, the customs may consider that you may sell the second laptop, or you will be using it for commercial activity (to establish an office, for example). In that case, they will sum up their total cost and you will have to pay 30% (that is, if the value of the both laptops is valued at $4000, you will pay $1200).
(с) http://waytorussia.net/Practicalities/Customs.html
Какими документами эти вопросы официально регулируются/описываются? И как с этим вопросом на деле? Если ноута два, как на границе определят, больше ли $4000 суммарная стоимость? И, по идее, бизнес-виза как раз и предполагает commercial activity... Но это все так себе источники информации, конечно.