When Nevada voters go to the polls Nov. 7, they will be asked to repeal a long-ignored state constitutional provision prohibiting women and persons who have engaged in duels from holding public office.

Passage of the initiative is not in doubt. But its presence on the Nevada ballot is testimony to the obstacle of tradition that faces sponsors of the Equal Rights Amendment here as they try to win approval of another ballot provision favoring ERA.

The Church of Jesus Christ of later-day Saints (Mormon) is adamantly opposed to the amendment, and its members constitute an estimated one-fifth of the state's voters. Excerpts from an address by Mormon official Roger Hunt of Las Vegas, widely circulated among members of the faith, claims that ERA will wipe out "protection" women now enjoy from divorce laws, as well as pregnancy leave, rights of privacy and exemptions from the military draft.

The ERA ballot issue in Nevada is the first test of the proposed constitutional amendment since Congress earlier this month added 39 months to the original seven-year period for states to ratify the measure.

For this reason, the issue is considered crucial by both sides. Though the Nevada ballot measure is only advisory to abide by the results that the vote is considered almost certain to determine the outcome of ERA in Nevada.

A victory here would be particularly significant for ERA advocates, who even with the extension, may have difficult time finding the three more states needed to make he amendment part of the Constitution. Thirty-five states have ratified thus far.

Since ERA expectations in Nevada are low, approval here would be certain to give supporters a much-needed boost.

And while the prevailing view here is that the ERA initiative will fail, some think the issue will be very close and that passage of the advisory issue is possible.

They point to straws in the wind such as the defeat of highly vocal woman senator who opposed ERA in the Sept. 12 primary - by a male candidate who favors the amendment.

And as Mylan Roloff, who heeds the "Equality Now" group pushing the initiative, observes, there is another tradition in Nevada that exists side by side with the prohibition on women and duelers holding office.

Nevada, she points out, was in many ways a "liberated" state before that word ever was used by the women's movement. In 1914 it became one of the first states to allow women to vote. It also was far ahead of most states in giving them an equal right to own property.

Because of the state's liberal and well-publicized divorce laws, career women and others who had to make a living on their own came to Nevada long before the phenomenon of working women was commonplace nationally. In both Reno and Las Vegas, women are conspicuous as employes of the state's No. 1 industry, gambling.

In Reno much of the spark for the ERA initiative comes from Sue Wagner, an articulate assemblywoman and the only female Republican in the legislature.

While the anti-ERA forces here have been running their campaign against the National Organization for Women, which they charge favors an alternative lifestyle that encourages homosexuality and permissiveness, the Nevada movement for ERA seems conservatively middle-class.

Wagner is described by friends as something of an All-American woman, complete with two children, a dog, hamster, five fish, a station wagon, membership in the Episcopal Church and a research professor husband who is for ERA because it is "unreasonable not to be."

She also is a tireless precinct worker who has canvassed 800 homes in her Reno district in favor of her candidacy and ERA. Both she and ERA are expected to carry her district, but the issue is in doubt statewide.

The outcome probably will be determined in suburban Sparks, east of Reno, and in Las Vegas, where the Mormon church is strong and could make a difference. There are Mormons, of course, who dissent from the official view on ERA and are on record for its passage, but their voices tend to be muted in Nevada.

The opposition is led by Jeanine Triggs, who has successfully persuaded the legislature to turn down ERA on two occasions. Triggs says that a decisive defeat at the polls is needed to take care of the issue "once and for all" in Nevada.

Both sides claim lack of money for their campaign, with proponents saying they will spend $70,000 and opponents $30,000.

But in a state where sentiment seems about evenly divided, there is a strong question whether the working women in the casinos and elsewhere will turn out in the same numbers as the church-oriented housewives.

"I think it's going to pass, I really do," says Roloff. "But the opposition has the edge because their vote is more dependable."