TALLAHASSEE, Fla. (AP) _ Two convicted murderers scheduled to die in Florida's electric chair Monday have won indefinite stays of execution in state courts.

The Florida Supreme Court, in a 5-1 opinion Thursday, delayed the execution of Sam Wilson Jr., who was sentenced to die for the 1980 murders of his father and 5-year-old cousin.

Terrell Johnson, condemned for two tavern killings, received an indefinite stay Wednesday from Circuit Judge Walter Komanski of Orange County.

Wilson's attorney, Ron Dion, a volunteer recently assigned to the case, won the stay after telling the court that previous attorneys were incompetent. He said one of Wilson's former lawyers said during appeal that Wilson was guilty of first-degree murder and deserved the death penalty.

''I submit this is hardly effective advocacy,'' said Dion.

He also said that that no one argued mitigating factors on Wilson's behalf, including the inmate's contention that the father and cousin were unintentionally killed in a prolonged family fracas and that Wilson showed extreme remorse.

Assistant Attorney General Joy Shearer, in arguing against a stay, said it wouldn't have done Wilson any good if his former attorneys had claimed he hadn't meant to kill his father and cousin.

''He used the hammer, he used the scissors, he used the knife. It was a prolonged attack on members of his family,'' she said. ''The state would have jumped all over that.''

Johnson was sentenced to death for the Dec. 4, 1979, slayings of a tavern owner and another man in the bar's restroom.

The judge said Johnson's lawyers discovered that he had never filed any motion for post-conviction release, a routine right given once to all Florida inmates in capital cases. His lawyers then filed that motion and asked for a full evidentiary hearing, requiring testimony, witnesses and the appearance of the inmate.

Wednesday's hearing was to determine whether such a hearing was necessary. The judge decided it was, requiring a stay of execution.