Even on "Alien Ressurrection" the two jointed leg detail is hardly noticeable since we only see the the alien walking erected on one very short shot after Elgyn´s dead
We see full body shots of the alien later on the underwater scene, of course but again it´s hardly to realize because they ar swiming, no walking.
Personally I didn´t realize to two jointed legs since two years later when I saw an Alien Ressurrection drone figure on a comic book London Shop called "Forbidden planet", and on those 2 years I have already seen the movie may times!.