IIRC lego had two actual patents: the basic brick, and the classic figure. The brick is expired while the figure isn't. Hence you can find "alternate" bricks, but not figures. They do own a shitload of trademarks, and aren't afraid to enforce them (which they legally must or they risk losing the TM).
Fun story: my wife ordered a couple of those "alternate" sets, and none inflicted on Legos patent nor TM (no lego branding, not a copy of a lego set, etc). The Swedish customs acted on their own (baffling to me) and stopped the package, sent her a letter in stark wording to accept forfeit. She challenged this, then Lego's lawyers got in contact with us and, using the figure patent, claimed this was a copy and we should forfeit or they would sue her. Very harsh letter, very stark wording.
Left a very bad taste in my mouth, haven't bought any Lego (or alternatives either) since.