President Carter yesterday sent to Congress the names of two nominees to judgeships on D.C. Superior Court, only weeks after the nominations had effectively been killed by the Reagan transition team in order that the new administration could make its own selections.

The nominations of Ricardo M. Urbina, a Howard University law professor who would be the first Hispanic named to the city's trial court, and Dorothy Sellers, a Washington lawyer in private practice, had been pushed by Major Marion Barry and other city officials. They had hoped that as a gesture in support of home rule, Reagan would give the necessary approval for confirmation.

Republican Senate leaders, however, who had also blocked confirmation of several federal judges, had declined to approve the local judicial nominees during the lame-duck session of Congress without a clear signal from the Reagan camp that it wanted them confirmed.

Herbert O. Reid, the mayor's legal counsel, said yesterday that he welcomed the nominations and hoped that "the matter had been cleared [with the Reagan administration.]"

"If Reagan's endorsement has not been secured," Reid said, "hopefully it is forthcoming. The city needs the court personnel as soon as possible."

Late yesterday it was not clear whether any agreement had been reached on the nominations. However, a spokesman for Sen. Charles McC. Mathias Jr. (R-Md.) said yesterday that news of the nominations had come as a surprise to the senator. Mathias' Senate subcommittee overseeing the District of Columbia has jurisdiction over city judgeships.

One Republican Senate source expressed surprise at the nominations, which he said appeared to be a challenge by Carter to Reagan. "It's a slap in the face at the new administration and an insult to the two nominees," the source said. "It makes them partisan nominations, when they should not be."

However, White House sources said yesterday that one of the reasons the president acted was the murky legal questions surrounding the nominations and what might have occurred if Carter had not sent the names to the Hill. Urbina and Sellers were nominated by Carter on Sept. 17 from a list of six names recommended by the D.C. Judicial Nomination Commission. When Congress adjourned last month withoug confirming the nominations, the nominations expired.

When Urbina and Sellers were originally nominated last fall, the time during which the president could act had almost run out. When the congressional session ended last year, it was not clear whether the 60-day time limit was restarted, or whether the president had to act within the first few days of the new session, which began this week. If the president does not act within 60 days of receipt of Judicial Nomination Commission recommendations, the commission sends nominations directly to Congress.

This is not the first time that a local judgeship nomination has been sent to Congress by a president who was about to leave office. Gerald Ford nominated several D.C. judges shortly before his presidential term expired, and when Carter took office he withdrew at least one of the names and submitted his own choice.

If Reagan's advisers decide that they in fact want to reserve the right to fill the two D.C. judgeships instead of letting Carter do so, they now must actively withdraw the nominations. Had Carter not acted, Reagan would have been able to fill the judgeships from the original list of six the commission sent to Carter, and would not have been limited to Urbina and Sellers.