Resolution
The usual path is to identify, keep and inactivate, then align the filings
In general, you inventory every related record, confirm whether they belong to the same legal person, keep the number that belongs to the company that is actually operating, take the extra number out of use, and point markings, insurance, BOC-3 and UCR at the number you will use.
FMCSA decides whether and when the public record changes. History on an extra number is not routinely moved onto the number you keep. This is not a guaranteed outcome or a fixed timeline.
See how resolution generally works