I wonder if you use in a tripple battle two helping hands one one Pokemon will the move boost 2 times or 1.5 x 1.5 times?
This question also includes flower gift instead of helping hand.
if helping hand is used twice on one Pokemon this would be the calculation:
1.5+1.5=3*the power of the move.
Source: math (Showdown doesnt have triple battles so I guess youll have to take my word for it :P)