A search of recent U.S. stamps for secret marks has discovered that two engravers etched their names onto the designs of two commemorative stamps in violation of government printing standards, officials said yesterday.

The discoveries bring to three the number of stamps with hidden marks since officials at the Bureau of Engraving and Printing disclosed earlier this month that they had found a tiny Star of David in the beard of Hebrew educator Bernard Revel on a $1 stamp.

The latest discoveries came as printing officials began a review of the print dies for the hundreds of U.S. stamps produced since 1980, a process expected to take 90 days.

Ira Polikoff, a spokesman for the bureau, said that the new discoveries, also difficult to detect with the naked eye, include a 1986 stamp celebrating stamp collecting and a 1985 stamp saluting World War I veterans.

Bureau engraver Thomas Hipschen worked his last name into the top of a stamp-canceling device in the 1986 stamp, and Czeslaw Slania, a Swedish government engraver, slipped his signature into the design of the stamp honoring the veterans.

A number of countries permit engravers to sign their stamps, but Polikoff said the United States is not among them. Slania, who has engraved stamps for a number of European countries, was recruited by the Postal Service to engrave the veteran's stamp.

Linn's Stamp News, which first reported the hidden marks, said in yesterday's edition that Slania has the "reputation of being a great joker." Because he is not a government employe, Polikoff said he is not subject to any disciplinary action.

Although Polikoff said it would be premature to discuss any disciplinary action against Hipschen, the spokesman said any engraver found to have violated the bureau's rules could be subject to actions ranging from a reprimand to dismissal.

Kenneth Kipperman, the engraver who placed the Star of David on the $1 stamp, has been removed from engraving duties at the bureau, a reassignment that followed his arrest this summer on charges of threatening to bomb the site of the Holocaust Museum near the Bureau of Engraving and Printing's 14th Street plant.

None of the secret marks are expected to enhance the value of the stamps because the marks were placed on dies from which all the stamps were reproduced.

Polikoff said that the bureau is taking the matter seriously because all the marks are considered "unauthorized" for its 16 bank-note engravers, who also work on the designs for U.S. currency. "They are one of our most entrusted groups of employes," he said.

The stamp collecting and Revel stamp are available at many post offices, but postal spokesman Hugh McGonigle said yesterday the agency has no plans to withdraw them from sale because the hidden marks are not considered offensive.

"It might have caused greater concern and led us to seek the stamps' immediate withdrawal from sale if they had been defamatory or derogatory," he said.

Polikoff said he believes the review will not uncover other hidden marks. "We have the feeling that there is nothing more," he said.