What if that kind of knowledge make him to forget his human memory? He was looking for knowledge, so I'm not sure he would be ready to forget anything. Besides, he maybe didn't need dragon wisdow to be wiser than them, if dragons respected him so much.
We never heard about Dragon Knights losing their memories, only about Dragon Slayers.
Besides, Maxos made those Dragon Knights... He obviously had to give them dragon knowledge! Without having that kind of knowledge, he wouldn't be able to do so, would he? It means he had that kind of knowledge, so he WAS a DK!
Besides Bellegar being Maxos... Is unlikely. Someone would recognize him. Zandalor? Behrlin, who fought him a few times? Other characters?
Maxos cared only for power and knowledge. Bellegar cares a bit about morality, doesn't seem obsessed about power and knowledge, he also cares about Rivellon in his own, strange, Bellegarish way...
But it also would be a good, surprising turn of events in next game! I still think that in Divinity 3, if it will contain a Dragon Knight, we will happen to be Maxos who has forgotten everything because of what happened, when he teleported somewhere in search of power (Patriarch said something about it - he was successful, but something bad happened after it). Surprising, great turn of events. ^^
