Upon pressing a key to open up either the creative inventory, or the chat box, there is a relatively large chance that upon pressing the key, another key press would be simulated without any real second key press. This only applies to Minecraft, and nothing else. For instance, pressing T at any speed to open the chat, has a change to simulate a second press, showing a t already in the chat box. This is the same thing for the / key as well. I know that this is not a one time thing, as I have restarted my MC, and PC multiple times, and found another issue like this on another forum.