Confirming seeing this too JAMF Cloud 10.12. When a new DEP item shows up as unassigned, the correct serial number is shown, model referenced as iMac 21.5", then the correct description for the MBP (or other portable) computer. Very odd indeed.

It gets weirder. A recent iMac 27" arrived with a serial number more akin to a MBP, starts with "C02" and not "Dxx". When checking coverage for the serial number, the correct iMac model is shown. Weird but functional.

Have you contacted your JAMF buddy to learn more?

yeah this is a glitch in the jamfmatrix, we've seen it as well. there is an older - but similar thread to this as well - https://www.jamf.com/jamf-nation/discussions/32082/dep-macbook-pro-model-says-its-a-imac-21-5-but-description-says-its-a-mbp-13-3