The Washington Redskins cut cornerback Wayne Davis for the second time in a month yesterday morning and signed cornerback Johnny Thomas.

Davis was cut at the end of training camp, then re-signed only last week after safety Clarence Vaughn suffered a knee injury that may yet require surgery. Davis played briefly in Sunday's 19-15 victory over Dallas.

But he is a cornerback by trade and the Redskins say they went for Thomas because he can play both safety and corner.

It was a return home, of sorts, for Thomas. He was a Redskins seventh-round pick in the 1987 draft and spent the year on injured reserve. He played in four games in 1988 before suffering a knee injury that required reconstructive surgery.

He was signed as a Plan B free agent by the San Diego Chargers in 1989, released last winter and signed by the Kansas City Chiefs, who cut him late in training camp.

The Redskins brought him in for a tryout Monday and signed him yesterday. He was one of the most popular Redskins in his days with the team, and one of the fastest.

"It's good to be back," he said. "I'd had a tryout with the Jets, but this is where I want to be. Everyone asks about my knee, but it's fine."Rypien Leaves Hospital

Quarterback Mark Rypien returned home from Arlington Hospital, the day after arthroscopic surgery on his left knee. He'll visit Redskin Park briefly today.

He was placed on injured reserve yesterday and his place on the roster was taken by Gary Hogeboom.