Perhaps you should read the .65 section that tells you that improvise if necessary to make sure your instructions are understood. As I stated '20 (twenty) followed by a two zero' reduces any confusion. 15 can sound like 50, etc., so restating the single numbers after the group form is a good practise to ensure pilot understanding. It doesn't tie up your freq any more and in fact reduces the possibility of having to tell a pilot twice.
Your quote was unclear. The parenthetical infers that "(two zero)" is the vocalisation because you wrote "20" and then, the parenthesis with "two zero".
To avoid confusion, your quote should have read:
"Turn twenty, two zero degrees right."
Improvisation is moot on this case, as it was never used, and the original order was never in the correct phraseology to begin with.
References: 5-6-1 711065R
[sic] 'Turn 20 (two zero)