For the first time since the armed forces seized power in a coup here 14 years ago, Brazilians are enjoying the pomp and spectacle of an election campaign in which more than one candidate is seeking the nation's top office.

As in years past, however, Brazil's 40 million voters are mere observers, excluded once again from the process of selecting their president.

On Oct. 15, the 590 members of a carefully screened "electoral college" will meet in Brasilia to choose one of two retired four-star army generals as president. As the standard bearer for ARENA, the official government party, Gen. Joso Baptista Figueiredo is virtually assured of victory over the opposition candidate, Gen. Euler Bentes Monteiro.

Even so, the two candidates are behaving as if the people were actually going to cast presidential ballots. Both have been crisscrossing the country in a U.S.-style campaign, addressing election rallies, making promises to supporters and skeptics alike, shaking hands and plugging their party's candidates in the congressional elections to be held Nov. 15.

At the same time, both candidates are engaged in extensive behind-the-scenes maneuvering as part of what political analysts here are calling "the real campaign." At stops along the campaign trail, the two generals are making a point of seeking out the most influential of their former colleagues in the military - which, as always here, will be the final arbiter.

For Brazilians, used to major decisions being handed down without any public discussion, even the trappings of a presidential election, with two military men airing their differences in the open, is a novelty. It has long been the policy of the armed forces to maintain a facade of unity in public. Military relations with the opposition customarily have been icy at best.

That tradition was broken on Aug. 23, when Bentes Monteiro, 61, a leader of a nationalist wing of the armed forces, agreed to accept the nomination of the only legal opposition party, the Brazilian Democratic Movement. His decision turned a simple rubber-stamp afair into what one newspaper here has sourly dubbed "the battle of the two generals for their fifth star."

Waiting in the wings as the military men court the public and key generals is Sen. Jose De Magalhaes Pinto, an ARENA dissident who announced his candidacy over a year ago. He says the population wants a civilian president and he offering himself as a compromise candidate in the event, however remote, of a crisis brought on by a deadlock between the military candidates.

In their numerous public appearances, the two generals have made it clear that they disagree on most major political and economic questions. Figueiredo, handpicked by the current president, Gen. Ernesto Gradual redemocratization" promised by Geisel but has also warned that the "revolution," as the authoritarian government here calls itself, will continue for as long as is necessary.

Bentes Monteiro, on the other hand, has pledged a return to civilian rule within three years, arguing that it is time for the military to head "back to the barracks." He has also promised sweeping economic reforms and hinted that he will place curbs on the activities of multinational companies whose presence Geisel has welcomed.

Confident of victory, Figueiredo and his advisers are now attempting to soft-pedal the issues and are concentrating on bringing out the candidate's personality in best Madison Avenue style. Unlike Brazil's four previous military presidents, who arrived in office as complete strangers to the public, Figueiredo, 60, has gone out of his way to talk with the press and meet with "the man in the street" in carefully staged encounters.

Under the tutelage of media specialists from the nation's largest advertising agency, Figueiredo has sought to project the image of a gruff and straight-talking man of the people. Almost nightly, television newscasts show Figueiredo in folksy scenes: Inviting workers to have drinks with him, kissing a "Miss Brazil" beauty contest winner, visiting his childhood home or tying the shoes of a kindergarten student.

Such gregariousness is a complete turnabout from the image Figueiredo projected during his four years under Geisel as the low-profile chiefs of the powerful and shadowy National Intelligence Service. Then, his grim and tight-lipped countenance earned Figueiredo the nickname in the Brazilian press of "the minister of silence."

The strategy of selling Figueiredo to the Brazilian public has sometimes been confounded by verbal gaffes and blunders that have left the candidate's staff visibly embarrassed. Figueiredo, a former cavalry officer, has said that Brazilians are incapable of voting for president because they cannot even learn personal hygiene. He has dismissed cattle farmers as "gigolos for cows" and declared that he prefers the smell of horses to that of the masses.

"Figueierdo's advisers would like for him to be a Harry Truman," said a Brazilian journalist who has worked in the United States. "But every time he speaks, I am reminded of the night Gerry Ford put his foot in his mouth about Poland."

Bentes Monteiro's advisers admit that their candidate has almost no support within the high command. They claim however, that the majority of colonels and lower-ranking officers are in the camp of their candidate and also point to the valuable services rendered on their behalf by Gen. Hugo Abreu, who was chief of Geisel's military Cabinet until resigning in January in protest against the selection of Figueiredo.

THe opposition general's only hope for victory in the "indirect" balloting is to win the votes of all 231 opposition delegates plus 65 ARENA dissidents. To do that, he must convince potential ARENA defectors that the armed forced will not intervene and annul the results in the case of an upset.

The Bentes Monteiro forces received a boost in morale last week when the son of former president Emilio Garrastazu Medici announced his support for the opposition candidate. That action was widely interpreted as the former president's stamp of approval for the Bentes Monteiro candidacy and as an indirect slap in the face to Figueiredo, who had been chief of the military Cabinet in the Medici government.

But the Geisel government seems determined to head off any groundswell for the opposition candidacy before it can get started. When Bentes Monteiro met with 24 officers at the home of a colonel during a swing through the northeast, the area where his military support is reported strongest, his host was arrested and another participant in the meeting immediately transferred to a remote post in the Amazon.