Dispatchers share threads, you run both of those coroutines inside a coroutine that uses Default dispatcher Each of dispatchers has own thread policy, but try to reuse existing thread to avoid context switch More details: https://github.com/Kotlin/kotlinx.coroutines/issues/261

I thought am not running on the same Dispatcher since I explicitly passing IO for the first one and Default for the 2nd one

You are not running on the same dispatcher, but dispatcher reuses a thread, created by another dispatcher