You can automatically create multiple UGens by providing an Array as one of the parameters. The SuperCollider interpreter will automatically create multichannel UGens as a result.

The following two examples produce equivalent output:

{ [ SinOsc.ar( 440, 0, 0.2 ), SinOsc.ar( 440, 0, 0.2 ) ]; }.play;

{ SinOsc.ar( [440, 440], 0, 0.2 ); }.play;

The second example can be easier to read, because it is obvious that only the frequency is changing - or in this case, that nothing is changing. This technique is more useful in a situation like the following:

{ SinOsc.ar( [[440, 445, 450, 455, 460, 465],
              [440, 445, 450, 455, 460, 465]],
             0,
             0.2 ); }.play;

That's not exactly easy to read, but it's easier to figure out than the most obvious alternative:

{
   [[ SinOsc.ar( 440, 0, 0.2 ), SinOsc.ar( 445, 0, 0.2 ), SinOsc.ar( 450, 0, 0.2 ), SinOsc.ar( 455, 0, 0.2 ), SinOsc.ar( 460, 0, 0.2 ), SinOsc.ar( 465, 0, 0.2 ) ],
    [ SinOsc.ar( 440, 0, 0.2 ), SinOsc.ar( 445, 0, 0.2 ), SinOsc.ar( 450, 0, 0.2 ), SinOsc.ar( 455, 0, 0.2 ), SinOsc.ar( 460, 0, 0.2 ), SinOsc.ar( 465, 0, 0.2 ) ]];
}.play;

More importantly, multichannel expansion gives us another tool to avoid repetition. Repetition is the enemy of correctness - it's so much more difficult to find a mistake in the second example than in the first!