I just thought Sifo Dyas was Palpatine stammering for a good cover name while on the phone placing the order:
My Name? Uh, Sidious.... Sid... Si... Si... Sifo.... Dyas. Yeah, that's it. Master Sifo Dyas.
My Name? Uh, Sidious.... Sid... Si... Si... Sifo.... Dyas. Yeah, that's it. Master Sifo Dyas.