The reason for the duplicate results is that your call to 'se_randomizeseeds' is using the system clock to set up the random number generators. So, because the workers are in sync, they're both getting the same value. You can get around this by explicitly passing a 'GlobalSeed' option to 'se_randomizeseeds'. Here's one way to do that, where we're using a combination of the current time:
parfor j = 1 : reps
seed = mod(floor((j/reps) * now * 8640000),2^31-1);
se_randomizeseeds(modelname, 'GlobalSeed', seed);
...
end
