PostgreSQL JOIN - Return NULL for duplicate results in left table

Question

I want to return some value in my query to 'null' if same or duplicates values

My query is like this:

SELECT 
        partner.nrp as nrp,
        partner.name                            as name,
        COALESCE(simp_wajib.savings_amount,0)   as simp_wajib,
        loan.id                                 as loan_id,
        COALESCE(loan.amount,0)                 as pokok_pinjaman
FROM(
SELECT  id          as id,
        name        as name,
        nrp         as nrp
FROM res_partner
WHERE anggota = True) as partner
RIGHT JOIN(
SELECT  anggota_id,
        savings_type,
        savings_amount
FROM basic_savings
WHERE billing_id = 46
AND savings_type = 2) as simp_wajib on simp_wajib.anggota_id = partner.id
LEFT JOIN(
SELECT  id,
        anggota_id,
        amount,
        amount_bunga,
        subtotal
FROM kopkar_loan_line
WHERE billing_id = 46) as loan on loan.anggota_id = partner.id
ORDER by name

Output below:

nrp	name	simp_wajib	loan_id	pokok_pinjaman
12345	Tony	20000	1	100000
12345	Tony	20000	2	50000

Expected output should be:

nrp	name	simp_wajib	loan_id	pokok_pinjaman
12345	Tony	20000	1	100000
12345	Tony	NULL	2	50000

I've tried several references but it doesn't work