I believe the Writing was giving the benefit of a doubt to the reader that when it is written the TEN commandments, which it is, the reader understands there are numbers one through ten commandments. It is written. Did you Google the information on organized cruelty to animals by parrishes in Spain? You have been quiet on the subject.
There are more than ten imperative statements in the passage we draw the ten commandments from. So in order to arrive at ten some have to be combined. Quite frankly I don't care if Spaniards have a longstanding tradition of throwing a goat out of a church tower in honor of a miraculous event in the life of a Saint (can't remember the story right now but I'll find it later).
Also I'm not entirely sure why you would object to the Catholic numbering since the traditional Jewish numbering of the commandments does the same thing.
Jewish numbering:
1. I am the Lord your God who brought you out of slavery in Egypt.
2.
You shall have no other gods but me.
3. You shall not misuse the name of the Lord your God.
4. You shall remember and keep the Sabbath day holy.
5. Honor your father and mother.
6. You shall not murder.
7. You shall not commit adultery.
8. You shall not steal.
9. You shall not bear false witness against thy neighbor.
10. You shall not covet.
Catholic/Orthodox/Lutheran numbering:
1
. I, the Lord, am your God. You shall not have other gods besides me.
2. You shall not take the name of the Lord God in vain
3. Remember to keep holy the Lord's Day
4. Honor your father and your mother
5. You shall not kill
6. You shall not commit adultery
7. You shall not steal
8. You shall not bear false witness
9. You shall not covet your neighbor's wife
10. You shall not covet your neighbor's goods:
Protestant numbering:
1.You shall have no other gods but me.
2.
You shall not make unto you any graven images
3.You shall not take the name of the Lord your God in vain
4.You shall remember the Sabbath and keep it holy
5.Honor your mother and father
6.You shall not murder
7.You shall not commit adultery
8.You shall not steal
9.You shall not bear false witness
10.You shall not covet anything that belongs to your neighbor
In this regard Protestants do not consider "I am the Lord thy God" a commandment and so they split the first commandment into two (in the Catholic numbering; it's the second commandment according to the Jewish numbering).