The other number is a part number, presumably for the label itself.
Most parts of an Xbox item will have it's own number, for example Project Spark has
Inlay: X19-38061-01
Disc: X19-38063-01
Insert 1: X19-38060-01
Insert 2: X19-38059-01
COA: X11-40709
The last part of the part number is usually used for additional editions or rereleases. The COA Part number does not need this so it is excluded.
The Part number can also be used to help identify where an item came from in some instances.
Puerto Rico COA: X17-90979
Mexico COA: X17-90978
So for example while searching I could see this listing was edited:
https://vgcollect.com/item/157809 with a Mexican COA which would separate it from a version such as
https://www.ebay.com/itm/374473653776 which is made in Puerto Rico.
Personally I haven't done much research into which Part numbers relate to which location but it could be a fun thing to look into at some point.
I don't have much knowledge on the 14 digit number. Personally I would speculate its relating to how many copies are printed as the numbers after the first 8 vary wildly. The first 3 digit combo seems to relate to the region (?) .
Eg in the case of Project Spark. 99991-292-000-000 - 99991-293-000-000 could be assigned to Europe while 99991-544-000-000 - 99991-545-000-000 Could be assigned to ntsc versions.