Comment 7 for bug 1788727

While it may be "by design," then the package system or something else is broken "by design."

On a system that uses signed kernels, the unsigned versions of the same kernels are also installed alongside. When I upgraded from 16.04 to 18.04, Grub choked because it found the unsigned kernels (which I wasn't even using).

Possibly the process behind installing signed kernels should be investigated? Currently, when you install the signed version via apt, this has a dependency on the unsigned version, both are installed simultaneously, and that doesn't seem like it should be the case.