select, modify, insert

I need to select some rows from a table based on a certain field, something like

select * from table where ts=100

On these rows, I need to edit the value in ts to current value (100 in the above example) and increase it by a constant amount (say 50 so that new value is ts=150 for all these rows)

While retaining the old rows in the table, these new rows also need to be inserted into the table.

e.g. If the table was

ts        A       B     C
100     x       y      z
90       a       d      f
30       s        y     z
100     c        v     b

Then new table would be
ts        A       B     C
100     x       y      z
90       a       d      f
30       s        y     z
100     c        v     b
150     x       y      z
150     c        v     b

Using PostgreSQL