https://christiananswers.net/q-eden/edn-r010.html
When Mary Ann Pakiz converted to Catholicism she was told to burn her King James Version Bible. She eventually entered the Order of St. Benedict. Despite her devotion, only years later did she become a true follower of Christ. Here is her fascinating story in her own words, explaining what she was taught in the Catholic Church, what was wrong with it, and why she came to the personal conviction that the only way she could truly follow Christ was to leave the Catholic church. She explains why she is now confident and at peace about her final destination, Heaven.
Because Protestants use the 10 Commandments found in Exodus. Catholics use the formulation found in Deuteronomy, which combines the first two Exodus commandments and distinguishes thy neighbor's wife from his property.
Go read Deuteronomy 5 again. The 2nd commandment is not lumped in with another one but a distinctly different snd unique "Thou shalt not..." all its own.
I think the real reason the catechism omits the 2nd commandment is because Catholicism is a mashup of Roman paganism and early Christianity complete with idol worship and prayers to angels, saints, etc. and the 2nd commandment contradicts your doctrine too much.