PS - what you can also do is get a copy of your credit report and see what information is being reported about this other bankruptcy. There is a service called PACER - an attorney who is registered could look up this case if it is in PACER. The attorney could review this case and if its for another debtor, maybe who has your same name or a very similar social security number, then you would include a printout of that other case as well in your dispute letter to the credit bureaus and to the lender to support the fact that the other case pertained to some other person, not you.

I have PACER access and could obtain this information or do the dispute letters for you for a reasonable fee.

Then the credit report is in error. Have you disputed this with he credit bureaus? There is no way to prove the absence of something. Obviously there would be no filings so the burden should be on the credit bureau to prove that there is another listing.

There should be a record of the one bankruptcy that you filed. You need to write a letter to the credit bureaus explaining that you filed (attach a printout of your discharge order) and dispute any information pertaining to any other bankruptcy.

This is all going to take time. You should have gotten your credit in order BEFORE you started applying for a mortgage. There is a process with some lenders called Rapid Re-Score. For some clients, I have sent letters to the mortgage lender explaining what is going on and I provide a copy of the dispute letter sent to the credit bureaus. What I would do is make a copy of the dispute letter and send it to the mortgage lender with a copy of your bankruptcy discharge and tell the lender you only have one bankruptcy not two and ask that the lender do a rapid re-score on you.