Hook callback not called if hooked method is called from an other hook

[MPeti1]

If I call firstMethod() from secondMethod()'s callback, then firstMethod()'s callback doesn't get called. But then what is the purpose of XposedBridge.invokeOriginalMethod()? I mean, that should only happen if I call firstMethod() through XposedBridge.invokeOriginalMethod().
Is this a bug, or do I misunderstand something?