SELECT
ccy.id,
regexp_replace((SELECT listagg(column_value,'; ') within GROUP (ORDER BY column_value) FROM TABLE(ccy.ccys)),'([^;]+)(;\1)+','\1') AS Currency,
regexp_replace((SELECT listagg(column_value,'; ') within GROUP (ORDER BY column_value) FROM TABLE(ccy.linenum)),'([^;]+)(;\1)+','\1') AS Linenum
    from (SELECT mandate_id, COLLECT(line_num)linenum,COLLECT(currency_id) ccys
    FROM t1 WHERE active='Y'
    GROUP BY id)ccy
 where ccy.id='746'

Table data		
		
ID	Line Num	Currency
746	1	CHN
746	1	JPY
746	1	USD
746	2	INR
746	3	GBP
746	3	HKD
746	5	CHN
746	5	JPY
746	5	USD
		
Output		
ID	LINE NUM	CURRENCY
746	1;5	CHN;JPY;USD
746	2	INR
746	3	GBP;HKD

SQL> select  *
  2    from  tbl
  3  /

        ID LINE_NUM CURRENCY
---------- -------- ----------
       746        1 CHN
       746        1 JPY
       746        1 USD
       746        2 INR
       746        3 GBP
       746        3 HKD
       746        5 CHN
       746        5 JPY
       746        5 USD

9 rows selected.

SQL> column line_num format a10
SQL> column currency format a11
SQL> with t as (
  2             select  id,
  3                     line_num,
  4                     listagg(currency,',') within group(order by currency) currency
  5               from  tbl
  6               group by id,
  7                        line_num
  8            )
  9  select  id,
 10          listagg(line_num,',') within group(order by line_num) line_num,
 11          currency
 12    from  t
 13    group by id,
 14             currency
 15    order by id,
 16             line_num
 17  /

        ID LINE_NUM   CURRENCY
---------- ---------- -----------
       746 1,5        CHN,JPY,USD
       746 2          INR
       746 3          GBP,HKD

SQL>