Spain Civil war 50 centimos coins

I recently acquired the 50 Centimos Santander, Palencia  coin with the PJR and one without the PJR.  They are the proper width, but vary in the weight.  The PJR weighs 2.80 grams and the w/o PJR weighs 2.64 grams.
Are these coins known to vary in weight like this?

I have found that there are 4 versions of this coin and the weights from different sources are erratic, but they fall between 2.4gm up to 2.8gm.

Thanks, I have a tipo 2 and tipo 3.  Should this be modified on the catalog listing?