FREDONIA, N.Y. (AP) _ In 1933 when the Marx Brothers made the movie ''Duck Soup'' with its setting in the mythical kingdom of Freedonia - with two E's - Fredonia Mayor Harry B. Hickey complained to Paramount Pictures.

''The name of Fredonia has been without a blot since 1817,'' Hickey said. ''I feel it is my duty as mayor to question your intentions in using the name of our city in your picture.''

The Marx Brothers fired back this reply:

''Your excellency,'' they wrote. ''Our advice is that you change the name of your town. It is hurting our picture. What makes you think you are mayor of Fredonia? Do you wear a black moustache, play the harp, speak with an Italian accent or chase girls like Harpo? We are certain you do not. Therefore, we must be the mayor of Fredonia, not you.''

Thus began the historic connection between the zany brothers and this western New York college town, a link to be honored Saturday in the second annual Freedonia Marxonia Film Festival and Symposium.

About 1,000 people wearing Groucho glasses and noses are expected at Fredonia State College for a group picture in the afternoon. But that's not all.

There will be a serious speech by Marx Brothers expert Paul G. Wesolowski and a non-serious duck soup competition. How non-serious? Well, last year's winning entry was by student Karen West, who submitted a pet mallard duck paddling around in a washtub among turnips and carrots.

The Post Office has thrown itself into the spirit of things and will be canceling stamps with a postmark that shows Groucho, Harpo and Chico and has the extra ''e'' in Fredonia.

Postmaster Robert Kaus says he's gotten about 150 requests for the cancellation, some from as far away as Belgium, Italy, and the Soviet Union.