The license has changed from MS-PL to Apache 2.0 relatively recently (previously it was licensed under MS-PL, and the announcement has changed here ). I think you can safely assume that it is licensed under Apache 2.0, because that is what the team intends. As far as I can tell, this is just a packaging error, and the license distributed with the installation should also be Apache 2.0.
I am not a lawyer, but I think it may be possible to issue the code under several different licenses if you own it, so it may be that the installation of MS-PL is licensed legally, and the online source Apache 2 is licensed. (Even if it is not intentional.)
However, both licenses allow you to perform essentially the same things, so this should not be a problem.