gacha

Galahad isn’t a (True) Alter. He has no idea why he’s been summoned as an Alter and is noted to be a ‘Heroic Spirit bathed in fantasy’ and hints that he didn’t even exist. Anubis confirms it later where he says Galahad Alter is an existence solely dependant on the true Galahad’s fame and prestige.

More information. Anubis goes on to talk about how the Requiem Grail can’t outright control what it summons, but it can change it. It recognised Galahad as a threat to its control and fucked his shit up. Otherwise Anubis notes that Alter’s power is nowhere near the original and that the actual Galahad’s Noble Phantasmal would be beyond anything summoned in the world of requiem. And that even his authority would have no chance before them.