Implement more than one interface with object expressions

General
1 
type IRunnable =
    abstract member Run: unit -> unit

type IPrintable =
    abstract member Print: unit -> unit

type Service() =
    class
        interface IRunnable with
            member _.Run() =
                backgroundTask { printfn "run" } |> ignore

        interface IPrintable with
            member _.Print() = printfn "print"
    end

let env =
    { new IPrintable with
        member _.Print() = printfn "print"
      interface IRunnable with
          member _.Run() =
              backgroundTask { printfn "run" } |> ignore }

let print (x: IPrintable) = x.Print()
let run (x: IRunnable) = x.Run()

let doIt (env: #IPrintable & #IRunnable) =
    print env
    run env

doIt env // <- error: 
(* 
The type 'IPrintable' is not compatible with the type 'IRunnable'. Why? 
*)

let env = Service()
doIt env

I do not understand why got error.
I think env and Service type re equal.

It is works, but it lost meaning
to use expressions


type IPR =
    inherit IPrintable
    inherit IRunnable

let env =
    { new IPR with
        member _.Print() = printfn "print"

        member _.Run() =
            backgroundTask { printfn "run" } |> ignore }