I can't find a mixture (or absence) of quoting that makes this work in the GUI console:
addmultisigaddress 2 '["02404c0b780b0d3f70a57bccb0cac31c77e980d899db00f04a61052cf6500bde23","02092eb733ce9027fcddb9917e841057c747318ff973de7a7768da9b3f039d6892"]'