If I recall correctly, there was a member here a year or so ago who withdrew a K-1, then "rescinded" the withdrawal. All went well until an I-485 was submitted. USCIS found the original withdrawal. I think the solution was to file an I-130 and a new I-485 since the beneficiary was already in the US. There are also other cases, in VJ history, in which USCIS later discovered withdrawn petitions. This has happened as late as N-400 adjudication. In one case, USCIS made an exception and allowed the petition to remain valid. I would think the best practice resolution for anyone who wants to rescind a withdrawal is just to file a new petition.