Yoda recognized R2 in ESB according to "From a Certain Point of View: ESB"

“Carefully moving through the swamp while staying beneath the fog, Yoda soon spotted the boy and his droid unpacking their supplies. Even though the droid was caked with algae, dirt, and stomach fluid, its appearance and familiar blips were still quite recognizable.R2-D2.“Of course the boy had Anakin’s old droid with him. Such cycles of fate no longer surprised the nine-hundred-year-old Jedi.” via /r/StarWars https://ift.tt/2X5WAQr