This is not the norm, it should not be required. The only time I have ran into this issue is on my "Arduino on a breadboard" (aka my homemade one), where I had to hold the reset button as the code uploaded or it would fail.
Something is wrong. It could be on the computer or on the Leonardo.
Other boards use a real reset when a sketch is uploaded, but the Leonardo has a different sequence. You create a real reset by pressing the reset button.
You could try to re-install the drivers for the usb-serial. Since two Leonardo boards have the same behaviour, it is most likely a driver problem on the computer. Open the Device Manage and look for the COM ports. Update the drivers by selecting the drivers in the Arduino folder.
I hope you use a new version of the Arduino IDE ?
You could also try to re-write the bootloader on the Arduino boards. You need a programmer for that.
While this probably isn't your exact problem it may be helpful.
