Twin-gate structures consisting of the series combination of two short-channel SOI MOSFETs of different lengths with a common gate have previously demonstrated kink-free and very flat output characteristics. The authors observe and explain that when using long-channel fully-depleted twin-gates a kink-like effect reappears and seriously damages the output conductance.
Deceuster, D., & Flandre, D. (1994). Kink-like Effect in Long N-channel Twin-gate Fully-depleted Soi Mosfets. Electronics Letters, 30(17), 1456-1458. https://doi.org/10.1049/el:19940992 (Original work published 1994)