A winning Sandown treble for leading trainer Darren Weir has been soured by a $3000 fine from Racing Victoria stewards.

Two of Weir's three runners in the final event on Saturday were presented in the mounting yard wearing the wrong saddlecloths.

Noela's Choice and Stylish Miss, numbers eight and 12 respectively, entered the mounting yard wearing each other's saddlecloths.

The mistake was picked up by the starters who were checking the brands before jockeys were mounted.

As Weir had left the course, his representative Darren Murphy took full responsibility for the mistake.

"I apologise on behalf of myself and the staff," he told stewards.

In a telephone hook-up during the inquiry, Weir told stewards the only defence was that both horses, chestnut mares with white faces, looked the same.

Acting chief steward Rob Montgomery said the starters had averted a disaster.

"If the starters didn't pick it up checking the brands the situation would have been a 'don't come Monday' mistake," he said.

Cannyescent won the 1400m benchmark race, with Data Point second and Thelburg third.

Stylish Miss finished eighth under Jye McNeil, with Noela's Choice last for Dean Yendall.