Can I connect two LEGO EV3 via USB to Matlab?

I have two LEGO EV3 bricks which I want to connect and control in Matlab 2019a.

However, when I run the command:

myev3 = legoev3('USB');

only one of them connects. So I am starting to guess that there can be only one legoev3 object connected.

I also tried to connect one via bluetooth and one via USB by the following code

myev3_1 = legoev3('Bluetooth','/dev/tty.WALL-E-SerialPort');

myev3_2 = legoev3('USB');

But the connection to the usb marks an error:

Error using legoev3 (line 307)

Failed to connect to EV3 through USB. Please check your

USB connection.

Error in untitled (line 15)

myev3 = legoev3('USB');