FAKE question about parameters

build.cmd

@echo off
cls
"NuGet.exe" "Install" "FAKE" "-OutputDirectory" "packages" "-ExcludeVersion"
"packages\FAKE\tools\Fake.exe" build.fsx %*
pause

build.fsx

// include Fake lib
#r @"packages/FAKE/tools/FakeLib.dll"
open Fake
open Fake.EnvironmentHelper

// Default target
Target "Default" (fun _ ->
    trace "Hello World from FAKE"
)

Target "Clean" (fun _ ->
  printfn "Name = %s %s" (environVar "first") (environVar "last")
  trace "Cleaning up your trash"
)

Target "Random" (fun _ ->
  printfn "Name = %s %s" (environVar "first") (environVar "last")
  trace "It's not really random"
)

Target "What" (fun _ ->
  printfn "Has build param WAT? %A" (hasBuildParam "WAT")
  printfn "Has build param YO? %A" (hasBuildParam "YO")
  printfn "Has build param YOLO? %A" (hasBuildParam "YOLO")
  printfn "Name = %s %s" (environVar "first") (environVar "last")
  trace "What happened?"
)

// start build

printfn "Build is starting, sit down and enjoy the ride!"

"Clean"
  ==> "Default"
    ==> "Random"
  ==> "What"

RunTargetOrDefault "Default"

commandLine

    .\build.cmd What -ev first john -ev last doe

Prints:
    
    Has build param WAT? false
    Has build param YO? false
    Has build param YOLO? false
    Name = john doe
    
As expected. But this

    .\build.cmd What -ev first john -ev last doe WAT YO

prints: 
    
    Has build param WAT? true
    Has build param YO? true
    Has build param YOLO? false
    Name = true true
    
And this prints what I expect

    .\build.cmd What first=john last=doe WAT YO
    
Prints    
    
    Has build param WAT? true
    Has build param YO? true
    Has build param YOLO? false
    Name = john doe