This topic is covered here in the documentation. You should not mix setting 'Seed' with setting 'Substream'. (The 'Seed' value sets up the state of the random number generator in a different way, and does not give you the control you need in this situation). So, you should modify your code slightly to do this:
% Use parallel.pool.Constant to hold a RandStream on each worker
sc = parallel.pool.Constant(RandStream('mrg32k3a'));
parfor ii = 1:60
% Get the stream value
stream = sc.Value;
% Set the Substream
set(stream,'Substream',ii);
% Make this stream the default (for normrnd etc.), and store
% the old value for later.
oldGlobalStream = RandStream.setGlobalStream(stream);
par(ii) = rand(stream); % Or you could just call rand()
% At the end, you could restore the old global stream
RandStream.setGlobalStream(oldGlobalStream);
end
Here I've used RandStream.setGlobalStream to set up the stream for normrnd, and reverted at the end of the loop iteration.
