Apple is mostly to blame for this, as they have for many years now been reusing model identifiers across upgraded models of the same line. So for example, your 2015 and 2017 MBAs are essentially the same computer, but with the 2017 one having slightly bumped specs. Apple has chosen in those cases to just reuse the same model identifier, which is plumb stupid in my opinion, since they are NOT technically the same machine. I'm not sure why Apple is so averse to using a new model identifier, but that's a topic for another discussion.
This in turn, messes up Jamf's lookup process as they are using an internal lookup table of some kind to match model identifiers with the full model name. That part is on Jamf, since there are some somewhat better, but more involved ways of looking up the correct model that they should be using.
I'll direct you to a few Feature Requests that ask for this process to change so you can vote it up. And also because in the FR posts there are some solutions mentioned that get around this problem, but they require using an Extension Attribute.
https://www.jamf.com/jamf-nation/feature-requests/2567/match-on-model-number-instead-of-model-identi...
https://www.jamf.com/jamf-nation/feature-requests/2214/fix-inconsistent-naming-of-macs-in-the-invent...
