The TAB has come under further pressure to dispense with fixed-odds head-to-head betting - from another trainer of a horse involved in the David Walker scandal and a former boss of the Racing Integrity Unit.
But while Masterton trainer Stacey Dougan is adamant the bookmaker option has to go, she is more forgiving of Walker.
''I couldn't believe it when they [racing integrity investigators] told me David had bet against my horse when he rode it at Waverley,'' Dougan said.
''That bet has to be stopped, it's just too tempting for people.
''He can't be the only one doing it.
''Maybe he's the only one who has been caught.''
Dougan said she was pretty upset to hear the allegation Walker might not have ridden Lil Mer on her merits.
''I called him and told him as much and he was as remorseful as heck. He said he did bet on the other horse but he promised me he did not pull mine up.
''David has been good to me in the past and I'm prepared to give him a second chance.''
Dougan said she was disappointed in Lil Mer finishing only 10th of 12 in the race on July 31, given she had run in the first four in eight of her previous 13 starts.
But she put it down to the fact the mare drew the outside gate and was racing in blinkers for the first time, and had done a few things wrong.
''David told me after the race to take the blinkers off because she had reefed and pulled with them on.
''And I know she's not an easy mare to ride.''
Meanwhile, former Racing Integrity Unit boss Cameron George said he was totally opposed to head-to-head betting.
George, now chief executive of the Auckland Racing Club, said the option had to be questioned.
''It makes no sense to me. Apart from the integrity perspective, jockeys have an obligation to animal welfare. If their horse is beaten, they've got to look after it, not push it out to beat another horse home.''
George said he spent several years lobbying New Zealand Thoroughbred Racing to stop jockeys from betting and conform to international standards.
''But when they didn't agree, we had to put control mechanisms in place to police it as best we could.''
Racing Integrity Unit operations manager Mike Godber said that while the unit had discussions with the codes about the rules it ''had no public position'' on head-to-head betting.