This isn't possible. In Stratum, each miner has a unique ExtraNonce1 value which means giving every miner the exact same job (which is what Stratum does already) will result in different hashes from every miner. There is no way around this, since if you added a feature to Stratum that forced an ExtraNonce1 change for work verification, the withholder would KNOW they're being tested.
Thank you for your answer
I suspected a little it was not so easy!
Remains a statistical analysis, but the scale of a pool, it may get a lot of warnings, only the larger miners will be effectively been verified.