Thanks for the information on those languages.
In my opinion, its a good idea to learn multi languages, 3-5 is a good number.
Also the decision on what language you should learn depends on what do you want to do.
If your goal is to build a web application, then probably C++ is not a good idea, though its a great advantage to have C++
If your goal is to learn something to find a better job, then you have to see the market needs. For example here in UAE most government entities are going for Microsoft products, that means ASP, C#, and VB will grant you more points over PHP, Python, and C++ in most cases.
But that doesn't mean you shouldn't learn other languages, even if you think you will not use them.
If you never made a mistake, you never tried anything new.