Join and combine tables to get common rows in a specific column together in Postgres - postgresql

Question

I have a couple of tables in Postgres database. I have joined and merges the tables. However, I would like to have common values in a specific column to appear together in the final table (In the end, I would like to perform groupby and maximum value calculation on the table).
The schema of the test tables looks like this:
Schema (PostgreSQL v11)
CREATE TABLE table1 (
id CHARACTER VARYING NOT NULL,
seq CHARACTER VARYING NOT NULL
);
INSERT INTO table1 (id, seq) VALUES
('UA502', 'abcdef'), ('UA503', 'ghijk'),('UA504', 'lmnop')
;
CREATE TABLE table2 (
id CHARACTER VARYING NOT NULL,
score FLOAT
);
INSERT INTO table2 (id, score) VALUES
('UA502', 2.2), ('UA503', 2.6),('UA504', 2.8)
;
CREATE TABLE table3 (
id CHARACTER VARYING NOT NULL,
seq CHARACTER VARYING NOT NULL
);
INSERT INTO table3 (id, seq) VALUES
('UA502', 'qrst'), ('UA503', 'uvwx'),('UA504', 'yzab')
;
CREATE TABLE table4 (
id CHARACTER VARYING NOT NULL,
score FLOAT
);
INSERT INTO table4 (id, score) VALUES
('UA502', 8.2), ('UA503', 8.6),('UA504', 8.8);
;
I performed join and union and oepration of the tables to get the desired columns.
Query #1
SELECT table1.id, table1.seq, table2.score
FROM table1 INNER JOIN table2 ON table1.id = table2.id
UNION
SELECT table3.id, table3.seq, table4.score
FROM table3 INNER JOIN table4 ON table3.id = table4.id
;
The output looks like this:
| id | seq | score |
| ----- | ------ | ----- |
| UA502 | qrst | 8.2 |
| UA502 | abcdef | 2.2 |
| UA504 | yzab | 8.8 |
| UA503 | uvwx | 8.6 |
| UA504 | lmnop | 2.8 |
| UA503 | ghijk | 2.6 |
However, the desired output should be:
| id | seq | score |
| ----- | ------ | ----- |
| UA502 | qrst | 8.2 |
| UA502 | abcdef | 2.2 |
| UA504 | yzab | 8.8 |
| UA504 | lmnop | 2.8 |
| UA503 | uvwx | 8.6 |
| UA503 | ghijk | 2.6 |
View on DB Fiddle
How should I modify my query to get the desired output?