For the second time in less than six months, the Metropolitan Museum has been hit with a lawsuit claiming it misleads people into thinking they have to pay admission, rather than being asked to part with a suggested donation. The first suit, by two longtime members, came last November. This most recent one, by two patrons from the Czech Republic and one from Manhattan, alleges essentially the same thing: That the word “recommended,” written in small letters below the word “admission,” above the price list, does not make it clear the museum is free. The museum isn’t buying it. Spokesman Harold Holzer called the last suit “frivolous” and the most recent one a “second attempt for publicity around the same baseless lawsuit that was filed a few months ago.” The museum’s lease says it has to be free a few days a week, but admission has been voluntary since the 1970s.