I collect the different hilts on my Sentinel. And I have to have 2 since I dual wield.
For lightsabers specifically, some orange hilts are restricted to mainhand or offhand. It's actually a property of the item and not the mods so you have to watch out for that.
^ The above should be taken with two grains of salt and a fistful of "chill the F* out".
EDIT: Comment removed.
Question also answered.
Sorry