This is the text you quoted, but from the english version of the book:
Bonuses from metagenetic qualities that mimic certain cyber or bio-implants or vice versa are never cumulative.
This is talking about those specific qualities that mention that act like a cyber/bio-ware or mention that they do not stack. Otherwise, no metagenetic quality could be taken with enhancements to that same ability. Some examples include: 360-degree Eyesight, Animal Pelage, Bicardiac, Biosonar, Camouflage, Dermal Alteration, and many others.
A more specific example of this kind of quality that will not stack with enhancements that provide a similar bonus:
The character develops a pocket-like pouch on her chest or
abdomen, just like the pouch a kangaroo uses to carry its young.
This pouch is equivalent to a Skin Pocket (p. 339, SR4).
Double Jointed is a positive quality, not an enhancement. It also does not mention that works like any cyberware or bioware, or that it is incompatible with them. As such, it should stack with any enhancements you got.
Cost: 5 BP
A Double Jointed character has unusually flexible joints and can bend and contort his body into extreme positions. The character receives a +2 dice pool modifier for Escape Artist Tests (p. 133). At the gamemaster’s discretion, the character may be able to squeeze into small, cramped spaces where less limber characters couldn’t fit.
Otherwise, it would simply state that you cannot benefit from wares, like High Pain Tolerance:
High Pain Tolerance
Cost: 5 BP per rating (max rating 3)
High Pain Tolerance enables a character to better shrug off the distraction of pain from his concentration. A character who possesses this quality can ignore one box of damage per rating point when calculating wound modifiers (see Wound Modifiers, p. 163). So a character with this quality at Rating 2 can take 4 boxes of damage without suffering a wound modifier. This quality may not be used with the Pain Resistance adept power, pain editor bioware, or damage compensator bioware.