IFC entities extracted twice

[gurbhej_singh]

Greetings for the day,
I am working with IfcOpenShell and Python on the extraction of IFC entities. I have developed a Python code which I want to use to extract the structural model from the architectural model. But there is an issue which I am not able to understand and resolve because I am a beginner.
When I try to extract the entities which do not contain any entity written in bracket the code runs accurately.
for example:- #1=IFCPERSON($,$,'',$,$,$,$,$);
#2=IFCORGANIZATION($,'',$,$,$);

But the issue occurred when I want to extract the entities with previous entities written in Brackets
for example:- #20=IFCPROJECT('f2535189_f2f3_445f_963',#5,'Unnamed',$,$,$,$,(#11),#19);

The issue was that when I try to extract the entity for example "IFCPROJECT", the code will extract the "IFCPERSON" and "IFCORGANIZATION" twice if I have already extracted these two entities as done in the code given below.

import ifcopenshell

f = ifcopenshell.open("C:\Users\GURBHEJ SINGH\Desktop\IFC\ModelFull.ifc")
f2 = ifcopenshell.file()

persons = f.by_type("IFCPERSON")
for person in persons:
    f2.add(person)

organizations = f.by_type("IFCORGANIZATION")
for organization in organizations:
    f2.add(organization)

personorganizations = f.by_type("IFCPERSONANDORGANIZATION")
for personorganization in personorganizations:
    f2.add(personorganization)

f2.write("test222.ifc")

The output of the code was given below which is wrong:-

Output:
ISO-10303-21;
HEADER;
FILE_DESCRIPTION(('ViewDefinition [CoordinationView]'),'2;1');
FILE_NAME('','2019-04-11T13:41:16',(),(),'IfcOpenShell 0.5.0-dev','IfcOpenShell 0.5.0-dev','');
FILE_SCHEMA(('IFC2X3'));
ENDSEC;
DATA;
#1=IFCPERSON($,$,'',$,$,$,$,$);
#2=IFCORGANIZATION($,'',$,$,$);
#3=IFCPERSON($,$,'',$,$,$,$,$);
#4=IFCORGANIZATION($,'',$,$,$);
#5=IFCPERSONANDORGANIZATION(#3,#4,$);
ENDSEC;
END-ISO-10303-21;

The output I want was that their should not be repetition of entities:-

Output:
ISO-10303-21;
HEADER;
FILE_DESCRIPTION(('ViewDefinition [CoordinationView]'),'2;1');
FILE_NAME('','2019-04-11T13:41:16',(),(),'IfcOpenShell 0.5.0-dev','IfcOpenShell 0.5.0-dev','');
FILE_SCHEMA(('IFC2X3'));
ENDSEC;
DATA;
#1=IFCPERSON($,$,'',$,$,$,$,$);
#2=IFCORGANIZATION($,'',$,$,$);
#3=IFCPERSONANDORGANIZATION(#1,#2,$)
ENDSEC;
END-ISO-10303-21;

Please help me to resolve this issue.