The home movie of Marilyn Monroe banging John F. Kennedy and his brother Robert F. Kennedy ... will NOT be going up on the auction block ... TMZ has learned.

The Tulare County Sheriff's Department tells us the auction, which was scheduled to go down tomorrow ... has been canceled because William Castleberry -- the owner of the 8mm film -- settled his $200,000 debt.

Castleberrry owed the $200k for a previous court judgement against him -- and deputies had seiezed the film, along with several other items, to cover the debt.

Castleberry's attorneys tell us they have no idea who made the payment -- all they know is Castleberry's stuff will be returned ... and the world will have to wait to see Marilyn's alleged threesome with the Kennedy bros.
So who is this Castleberry that he would even be able to shoot or possess such a thing? I'd call bullshit but if the cops cataloged this thing as evidence.. too strange.