It is strange, but it is correct that a camera A noisier in most of the range, can have higher DR than a less noisy in most of the range camera B, as long as camera A gets less noisy than camera B in the deep shadows, where the SNR threshold is set for the DR criteria chosen.
But we are talking of the same camera here, and the 5D MKII will by certain be noisier in the _whole_ range at ISO3200 than at ISO100 for any given RAW exposure. So, if we assume DR is deeply related to noise (in fact it's just the range in which SNR does not fall below a chosen SNR threshold), I cannot believe by any means that the in-camera JPEG generation is so badly designed that produces valid information along a larger range at ISO3200 than at ISO100. And of course, the ISO100 image will be less noisy than the ISO3200 in the _whole_ range if RAW exposure is kept on both ISO settings, as is expected (i.e. shutter/aperture vary accordingly to the ISO set).