I just googled it. For example, here's what Samsung's website says in response to the question of whether you can charge both ways at once:
No, the device will be charged but only through the Wired charger. Even when the device started the charging through the wireless charging pad firstly and then was connected with wired charger later, the device will be charged only through wired charger.
But common sense should also tell us this cannot be done, we all own an electric car and we know what happens when it gets to 80% on a DC Fast charger... it slows down b/c you can only charge the battery so fast without causing overheating, exploding, fires, lol. Similarly, phones that have fast charging capability are likely going to charge as fast as possible already... you can't make it go any faster by trying two charging methods at once, the fast chargers are already configured to provide the fastest safe charging the phone is going to allow. Ultimately the phone won't permit it, which is the way it should be, just like the car won't permit DC fast to charge as quickly at 90% as it does at 50%.