Is it better to learn PHP first then ASP.NET second, or learn them at the same time?

I have been learning PHP for a while, and also want to learn C# and MVC. At the moment, is it better for me to concentrate all my power to conquer PHP first, then whenI can relatively masterfully use PHP, I can then start learning C# and ASP.NET?

I have this impulse to learn PHP and ASP.NET at the same time, but I just feel that I must master one first(relatively master it, I know it takes years to really master one thing). Many people say they first learned and did C++, and then when they need to learn Java, they found it very easily and can master Java really quick. So I think only after I finish learning PHP and do it for a while, can I feel that all these common things in web development that I learned in PHP are very similar to ASP.NET. If I haven’t finished learning one thing and start to learn another at the same time, it’s definitely a bad idea. Is my understanding correct?

Learning two new sets of programming languages is never a good idea, right?

PHP is easier to learn, if you are going to be a hobbist web developer you can go with PHP first. If you are a serious computer scientist, its better to pick up C#/ASP.NET first since the language encourages better OO practices. PHP can be used for multiple programming paradigms and different styles, its flexible but to some extent not good for developing good coding habits/standards.

thanks, I want to be a serious computer scientist.