If the loan was sold to another company, then the new company should still have all the loan documents intact. It sounds like they just need to issue a new loan number to identify your loan based on different numbering or identification standards for that company.
I wouldn't worry too much about it, unless they try to make you sign all new loan documents that don't happen to agree with what you have already negotiated with them.
If a different company is now handling your foreclosure/loan modification, it is entirely possible that it could change how they handle it due to a difference in processing, eligibility, and qualification requirements for that new company. Unless you actually came to terms with a loan modification with Aurora, then you don't have one, and you will be subject to whatever requirements exist for the NEW company handling your loan.