Can't offer any help, just wanted to commiserate with you. I'm trying to figure that one out myself, happened to me after I updated kopernicus and parralax (mind you not on a fresh install). Buttons start duplicating after scene changes (switch to another vessel, go back to the space center) each switch gains you more buttons. The ones duplicating seem sort of random, sometimes mechjeb or wolf or the stock buttons themselves. Another side effect is losing right click ability in flight after so long or too many scene switches. I Get it on 1.12.0 and 1.12.3. If I go back to my 1.12.0 install pre kopernicus and parralax update I'm fine...but I want the grass! Restarting does temporarily fix it but it comes back soon enough and it takes like 25 minutes to boot (too many mods) so doesnt really solve anything for me. Have replaced several mods but haven't found it, just trying to put off a clean install because I have a bad idea that's what it is. The fun part is this is the 1st thing that ever made me look for my logs to upload for help and apparently my game isn't making logs(player log yes output log no)