While I agree with the essence of Kyntestorme's post, I want to point out that you did not in fact 'ask him nicely' to remove it. Sarcasm and the use of the word 'please' after a demeaning sentence doesn't count.

I don't distinguish use of the left or right shift keys in any of my macro's, as far as the original point of this thread goes. However, I suspect that Bindpad [addon] does - I know I use it to differentiate different totem drops by binding one macro to 'numpad 3' and another to 'L-CTRL - Numpad 3', rather than making one macro with a modifier (which was also harder to modify on the fly).