high similarity between abnormal face images

Hi, I found that the model trained with AMS may get higher similarity bettem a pair of abnormal enroll and probe images (the probe is low qulaity, wrong aligned, or even not a face, the enroll is not a good id photo). The similarity may be around 0.4 or even higher while the ones trained with softmax may be just around 0. So have you ever met the same problems? Is it because that the margin push the feature space much compact than softmax?
Thanks!