If Trump really has tapes, he is much to smart to tell anyone. Why tip off people? Let them spin whatever lies they want, then he can play the tapes and prove all to be liars.
If he doesn’t have tapes, his claiming that he might may keep Comey and others from spinning too many tall tales, as they will be guarded in what they say, unsure if their conversations were recorded.
Think what would happen if Trump released tapes of his recording the FBI director?
That would be pretty bad for Trump and Comey.
Comey has to know they are real or he wouldn’t be playing CYA. Which is exactly what he’s doing.