Spurious casual type parameters on a method

```fsharp
type Class =
static member ProcessIEQ<'a when 'a:>IEquatable<'a>>(expected: 'a) = ()
Class.ProcessIEQ(0)
```

Hovering over `ProcessIEQ` in the last line gives:

- The formal generic argument `'a` has been removed.
- Two casual type parameters `'a` and `'0` (sorry I don't know the terminology for these - things that don't come directly after the method name as inputs) have been created in its place.

VS 17.14.6