no choice to remove or not accept double saber attachement???? why???

Serious answer here: Dual blade mode is an added gameplay functionality. It's a core element of how Cal behaves as a character in combat, so it's not just a cosmetic element like the saber parts. I totally agree that single blades are more interesting (I dance with a pair of single blades but typically fight with just one) but the dual blade has game mechanic reasons to be a functional part of Cal's loadoutonce acquired.