Seriously?

I've never heard anyone call anything coilover-related a "tap"

Twin-tube is a type of damper. There's another tube inside the body tube that the piston and valve sits in. On JIC's line, the A1's are twin-tube and the A2's are mono tube. A twin-tube damper generally has a smaller piston diamater which isn't really anything to brag about.

You're getting this confused with "double adjustable", which for all these low end coilovers means 2 places to adjust the ride height. (the other "double adjustable" means 2 places to adjust the damper). This type of mounting will have a threaded spring perch and a threaded lower mount. Generally it's these threaded lower mounts that can get you extra low.

These appear to be single adjustable for ride height.