trainingset =
ExampleData[{"MachineLearning","Mushroom"},"TrainingData"];
testset = ExampleData[{"MachineLearning","Mushroom"},"TestData"];
Train a classifier on a part of the training set:
SeedRandom[1234];
trainingSample = RandomSample[trainingset, 100];
c=Classify[trainingSample,Method->"GradientBoostedTrees"]
samples = testset[[All, 1]];

probs1=c[samples,"Probabilities"];
probs2=c[#,"Probabilities"]&/@samples;
probs1==probs2
True

trainingset = ExampleData[{"MachineLearning","Mushroom"},"TrainingData"];
testset = ExampleData[{"MachineLearning","Mushroom"},"TestData"];
samples=testset[[All,1]];
Do[
trainingData=RandomSample[trainingset,100];
c=Classify[trainingData];
Print@trainingData[[1]];
method=c[[1]]["Model","Method"];
probs1=c[samples,"Probabilities"];
probs2=c[#,"Probabilities"]&/@samples;
check=probs1[[All,1]]-probs2[[All,1]]//Chop[#,10^-5]&//Union;
Print[method,"=",check],{i,10}]