@BrandonY I just wanted to thank you for your suggestion. I had the exact same issue: typing "o" or "m" would show up as "om", and "f" was mapped to a right click. 7 was 7 and another key. Really annoying. I took the whole keyboard apart and cleaned each layer of the circuit membranes with a Swiffer cloth. I disconnected the power cable by mistake but was thankfully able to squeeze it back in properly. Totally saved me from buying another keyboard. Logitech K400R keyboard is now back to working perfectly.I know this is an old thread, but this was the closest hit to my problem when I searched.
My keyboard was giving me "om" when I pressed "o" or "m". It did the same thing on many PCs. I couldn't find any solutions online, so I figured I should open it up and check it out. I cleaned the inside a little, and gave the plastic membranes (in my rubber dome switch K400) a little wipe down. It didn't seem to work at first, but I tried again in a while and the problem went away. So I'm not sure what fixed it, but I guess it wouldn't hurt to open it up and clean and jiggle the parts around a bit. Just be careful not to snap any little ribbon cables while you're at it.