Nemesis Prime?

Joshua was angry his scientists made Galvatron's look based on Megatron instead of Optimus Prime.

His vehicle mode is a black colored Freightliner Argosy cab-over truck which doesn't make fit with Megatron or Galvatron since they usually go for a military vehicle (Cybertronian or Earth).

Also in Trasformers: Prime, Nemesis Prime had a similar story where he was a man-made Transformer.

 

The scientists didn't make him that way, Galvatron forced them to make him that way without them knowing it. But yes I think he's supposed to be their version of Nemesis

 

Joshua even says it in the movie. Galvatron was supposed to look just like Optimus and was goin to be used as a good TF in the public eye. He complains that it looks nothin like the design in the files and asks how it keep looking more like Megatron. So yes the Adgosy was supposed to be a human built Optimus/Nemesis Prime.

 

Which is really dumb when you think about it given - why would Megatron want to reveal that their Transformer is him so earlier before they acquire 'the Seed'

 

Megatron isn't a sneaky sort of guy. In fact he's kind of a megalomaniac who doesn't believe he can be defeated. And after being resurrected multiple times I don't see where he's wrong.

 

He probably just thinks us insects are stupid and wouldn't notice. a fair point though they probably should have realized what was going before Brains spilled the beans