Can I get raw mouse input as a WM_INPUT twice?

Question

I am trying to modify an existing application by adding an input gathering thread outside of its main thread.

The original application already processes mouse input pretty decently inside its main loop, but it does so at a rate that's very slow for my project to properly work.

So I want to process mouse input outside the main thread on a very high rate, without interfering with the original application's input handling process at all? How can I do that? Can I register a mouse device and get corresponding WM_INPUT without preventing the original app from doing its own processing untouched?