sbt IntegrationTest:definedTests also contains Test:definedTests

I have a problem running my unit tests in isolation from my integration test.

Running:

show it:definedTests

lists only my integration tests, but running:

show test:definedTests

lists both my unit and integration tests!

The relevant built.sbt config lines are set as follows:

scalaSource in Test := baseDirectory.value  / "test" / "unit" / "src"

Defaults.itSettings
fork in IntegrationTest := true
parallelExecution in IntegrationTest := false
scalaSource in IntegrationTest <<= baseDirectory( _ / "test/integration/src")
unmanagedJars in IntegrationTest := (baseDirectory.value ** "*.jar").classpath

lazy val IntegrationTestAltConf = config("it") extend(Test)

lazy val v4InternalAdmin = (project in file(".")).
  settings( Defaults.itSettings : _*).
  configs(IntegrationTestAltConf)

Can anyone point out what I've misconfigured?

Thanks