Who "buys" a mortgage from someone but lets the original owner continue to collect the mortgage payments??? I've never heard of such a thing. Course there are lots of things I've never heard of. When my mortgage was sold I started sending my payments to the new mortgage holder, not the original one.
Who are these investors you are referring to?
You may very well not have heard of such a thing and the governments and foreign investors of this world don't want you to hear of such things. They want us little people to be as ill-informed as possible, and not to ask too many questions. Unfortunately for them (see Ckblv's post), some folks are now starting to ask questions and insisting on answers. It will be interesting to see if they actually get any answers to their questions.
There is much that goes on behind the scenes that the average Joe knows nothing about but with this financial crisis, some of it may well be brought to light.