You say

In catalog item if i selected the security name the owner should auto populate.

How did you configure that?

Did you configure Auto-populate for Owner name, or perhaps created some Catalog Client Script?

By the way it is confusing to name references as Something name.

Just because the field is showing the name of Something, it is in fact a reference to Something sot it should be named Something.

Thus the not-confusing correct name for Owner name is Owner and for Security group name is Security group.

Only if Owner name would not be a reference but a single line text and it would contain the name of the owner, then it would be correct to name the field as such.