SQL & PL/SQL

I have tried in several ways to display a query where shows customer who have made more than 3 rentals from 01Nov to 31 Dec. However, for some reason the customerID column appear twice.

** I'm using 3 tables to get this result:

select RentalAgreement.membershipcardid as "MCardID",
customer.customerid,customer.cname,customer.address,
membershipcard.customerid,invoice.rentc,RentalAgreement.DateAndTimeOfIssue,
count(RentalAgreement.membershipcardid) as "NOfRents" from RentalAgreement,customer,membershipcard,invoice
where rentalAgreement.membershipcardid=MembershipCard.MembershipCardID
and customer.customerid = membershipcard.customerid
and RentalAgreement.DateAndTimeOfIssue between '01-Nov-2012' and '31-Dec-2012'
group by rentalAgreement.membershipcardid,MembershipCard.
customerid,customer.cname,customer.address,invoice.rentc,customer.customerid,RentalAgreement.DateAndTimeOfIssue;


MCardID CUSTOMERID CNAME ADDRES CUSTOMERID RENTC DATEANDTI
---------- ---------- ---------- ------ ---------- ---------- ---------
NOfRents
----------
107 27 EDuois N151AS 27 60 11-NOV-12
5

108 28 WDuois N151AS 28 60 19-NOV-12
5

101 22 ALuois N193AS 22 60 22-NOV-12
5


MCardID CUSTOMERID CNAME ADDRES CUSTOMERID RENTC DATEANDTI
---------- ---------- ---------- ------ ---------- ---------- ---------
NOfRents
----------
101 22 ALuois N193AS 22 60 21-NOV-12
5

101 22 ALuois N193AS 22 60 20-NOV-12
5

101 22 ALuois N193AS 22 60 24-NOV-12
5


MCardID CUSTOMERID CNAME ADDRES CUSTOMERID RENTC DATEANDTI
---------- ---------- ---------- ------ ---------- ---------- ---------
NOfRents
----------
109 30 ADDuis N151AS 30 60 03-DEC-12
5
Thanks for your time.
Im not sure if this query seems to be logic, I would appreciate any online guide for pl/sql