The `Install packages?` suggestion feature does not call `Set` to get the unique set of packages to ask to install

[anandijain]

julia> using ImageCore.FixedPointNumbers, ImageCore.ColorTypes
 │ Packages [ImageCore, ImageCore] not found, but packages named [ImageCore, ImageCore] are available from a registry. 
 │ Install packages?
 │   (jl_LTIgbR) pkg> add ImageCore ImageCore 
 └ (y/n) [y]: 
ERROR: it is invalid to specify multiple packages with the same name: `ImageCore`

It seems like it just naively iterates over these

[IanButterworth]

Thanks. Fixed in #42134