Honestly there isn’t much difference between these ingredients, so if you see them written on your medication, don’t worry.
Hydrochloride and Dihydrochloride are types of salts that are used to help your medicine dissolve in your stomach, and don’t interfere with the active ingredient.
This means that if you see that your medicine contains Cetirizine, Cetirizine Hydrochloride, or Cetirizine Dihydrochloride, you’ll still be getting the same active ingredient with the same level of effectiveness when treating your allergy symptoms.