I have an iPhone SE with iOS12, that was migrated from 5s a year ago, but in iTunes it shows its as iPhone 4s and iOS 8.3 and syncs to this. No other device is listed although it is in the Manage Devices list.
I cleared the 4s from the Manage Devices list in iTunes and deleted all the backups in ~/Library/Application Support/MobileSync/Backup/ but the issue persists.
So I'm unsure where its getting this incorrect info from. The SE used to show on the device list but not recently. The iPhone itself is labelled SE in Settings.