The only way you're going to get that much fuel into the oil sump, is from the carburetors .
I would check to see if your fuel tap is really shutting off the fuel flow, only other way to get fuel into the oil, is if a carb float valve isn't shutting off, but usually, you will get an external fuel leak from the carb bowl vent .
Was the bike on the center stand, or the side stand ?
These bikes don't like to be left on the side stand for an extended period of time .
If you were getting that much fuel past the piston rings, when the engine was running, I don't think the engine would be running very well at all .