create stig overlay

Hello,
I am quite new to this. I am trying to figure out how things works and how to use
compliance as code. I am interested in STIG compliance. 

As recommended, I ran the script called "create_stig_overlay.py". It created a
new  stig_overly.xml file. The file is interesting as it provide the link between STIG
rules and complianceascode rules. Is it correct? 
I noticed the script create a one to one relation between rules in STIG and rules in
compliance as code.
For instance the first STIG rule: "The Red Hat Enterprise Linux operating system must
be configured so that the file permissions, ownership, and group membership of system
files and commands match the vendor values. "
It mentions ownership and permission. The STIG profile in complianceascode has both
rpm_verify_ownership and rpm_verify_permissions.
But the created overlay only map to one of those rule .... and not always the same to the
stig rule above.

So my question: is this intended or is there an issue here? Or may be I missed something
else? 

If you have any comment to help me to progress, I will be gratefull.

Regards,
Marc