So J.O. are we to understand that CYYZ Tower controler let go of the transmit button {or foot key, if CYYZ tower has such things installed}}between the two "go around" calls, thus causing the "Air Canada" prefix to be dropped twice by ATC Net? If so it again is in conflict with SOPs ...
There is a short break between the two go-around calls on ATC Net. This is not unexpected given that it's pretty natural for a controller to assume that a crew is going to hear and follow the go-around instruction the first time.
If call sign is not used as tapes seem to show pilots did not need to go around unless they saw a conflict in my opinion.
The ATC tapes do not show that, they show the controller using the full call sign. Only a second hand scanner recording shows that, but that recording is not official evidence in an investigation.