Apparently roUrlTransfer are not re-entrant in regards to Async calls - at least you cannot have two calls concurrently on the same object. Since i see people started complaining only recently from these diagnostics, i presume they were added in v7.1. These are warnings btw (non-fatal).
I have no idea what the specific behavior is though, i.e. does the old request get ignored or the new one - but seems pretty clear it won't be both finishing successfully. So use a different roUrlTransfer. But keep references to both objects because if you drop one, so does the async call on it vanish :evil:
Once you've started an async operation (AsyncGet*/AsyncPost*) on a roUrlTransfer object, that object is busy until the operation completes.
If you call any function (well, most any function used for configuration or starting an operation, that is) on the roUrlTransfer while it is busy, that function call is a no-op and the diagnostic message is printed.