Washington and Miami players have decided to demonstrate union solidarity by shaking hands at midfield prior to their preseason game Saturday in Miami, according to Mark Murphy, the Redskins' player representative.

"We hope that the league isn't petty enough to try to prevent this," Murphy said about the gesture, which the National Football League Players Association hopes will help show the NFL that the players stand behind the union's attempts to negotiate a new collective-bargaining agreement.

The league has informed teams that players should be fined a minimum of $100 for any union gesture, calling such acts "violations of the antifraternization rule."

Redskins General Manager Bobby Beathard said the club has not decided what it will do if the midfield handshakes take place. He gave no indication that any attempt would be made to stop the players beforehand.

Coach Joe Gibbs said he was "not concerned" about any union action by his players. "I'm just trying to get my players ready for the regular season," Gibbs said.

But Miami Coach Don Shula expressed strong opposition to the proposed action. "I mentioned to them that I was strongly opposed to any action of any type and that I'll take whatever action I deem appropriate if and when." He would not speculate on what that might be.

Miami player representative Jimmy Cefalo said the players met for 35 minutes this afternoon and agreed to join the Redskins in the show of union solidarity.

"It's done before basketball games, done before boxing matches," said Cefalo of the handshaking plan. "We're just going to go out and shake hands with the Washington Redskins and then go out and try to beat them."

Meanwhile, Redskins owner Jack Kent Cooke said today the team's front office made an "incredible booboo" by denying some players expense money to a May minicamp and to this training camp.

"The front office acted entirely without my knowledge," Cooke said. "And they did so in direct contradiction of my policy toward my players . . . it was a stupid act and one which I cannot condone."

The Redskins decided Wednesday to pay the money in question. They had first told Murphy that it was not team policy to make the payments. The NFLPA had filed one grievance about the problem and was about to file another.