A bill that would have provided about 70,000 state employes with a form of collective bargaining died in the Maryland House today after twice failing by one vote to receive the constitutional majority it needed for passage.

In a voting foul-up that sent House leaders to their rule book, one delegate voted against the measure when she said she meant to vote for it. Then, when the vote was taken again, her "Yes" vote was canceled out when another delegate changed his vote from "Yes" to "No".

The bill failed both times by a vote of 70 to 57. It needed 71 votes, or a majority of the entire House, for passage. Under House rules, votes on proposed legislation can only be reconsidered once after a bill is voted down, so the measure is dead for this session.

The collective bargaining measure, although watered down to the point that unions were divided over its merits, was pushed by supporters as an important first step in giving state employes a stronger voice in labor negotiations.

It would have provided for binding arbitration of grievances but not of the contract agreement itself. Any contract disputes were to have been reviewed by fact-finders, who would issue advisory recommendations. Strikes would be prohibited.

Opponents of the bill argued that it was vague and would be too costly. They also said that several groups of state employes, including state troopers, college professors and firefighters, did not want to be included in the legislation.

After the bill failed by one vote, Del. Mary B. Adams (D-Baltimore) rose to say that she had meant to vote for the bill, and asked to have her vote changed. House Speaker Benjamin L. Cardin ruled that it was against the tradition of the House to change a vote if it would affect the outcome. She then asked to have the vote reconsidered.

On the second vote, although Adams voted for the bill, Del. Patrick C. Scannello (D-Anne Arundel) switched his vote and opposed it.

Adams refused to discuss how she had mistakenly voted against the bill the first time, while Scannello said that he had "changed my mind." He said he had decided the bill was too watered down and had sparked division among the unions.