I have 2 class label, but classifier model predicts 3 class?

My code is in Matlab. I have a binary classifier model with the labels (0 and .5), as it has been shown with black box in the figure:

However, when I am sending Test set to be predicted by the previousely trained Naive Bayes model,

   [pred_LF, score_f] = predict(Mdl_F,Feature_Test);

I getting 3 classes 0, .5, and 1 (red box):

I have already checked the values in training label, it is 2 two values. :(

Is there someone help me?! I am really confused why it is like this?! Your help is appreciated.