I need it concurrent some time before switch completely to 4.7.
I also noticed that both mgreq*. dll have same name, but tried to disable one in IIS when using other, and vice versa, and restart IIS each time.

When I had same case with previous concurrent versions eg 1.9/2.1, it wasn't case, IIS couldn't be confused because dll had different names.
Btw, also checked registry, and can find two different path to requester. Web config also have two.
Where is difference when decide which one will run after restart IIS?