A few years ago I rebuilt my Giant hybrid from the ground up. I replaced the front triple with a single and maintained the 9-speed rear, the shifter I used is a Shimano XTR SLM970. I am considering replacing the single with a double now, the single worked fine for me but I am looking to get my wife riding the hybrid, and I think going to a double up front would benefit her. Here is my question would a XTR SLM970 that is made for a triple, work with a double? Shimano makes a XTR SLM980 that can be switched from a 2 to 3 ring crankset...(my OCD kicking in) there are differences in the trigger and the cable adjuster, housing slightly different between the two, functionally the new version adjustable shifter would work great, it just wouldn't match the existing one.

Old version Shimano XTR M970 Rapidfire 3x9 Speed Left Shifter | eBay

New version Shimano XTR SL M980 2 3 Speed Left Shifter | eBay