"There are officially too many Megatrons here," he muttered, rubbing the back of his helm. "Are you telling me there's another one beyond Eyebrows, Autobot, and-- okay, I'm not calling him 'nice Megatron'. Miner. There's one more?"

That settles it. He's died and his spark has gone to the Afterspark which, in some sort of cruel joke, has given him not one but four Megatrons. There is no other explanation he will take at this point.