Update/Change all ID in PhpMyAdmin (MySQL)

Update/Change all ID in PhpMyAdmin (MySQL)

I've got a problem with a Joomla migration (Kunena forum component) When I
try to copy the old forum table to the new one, I receive "Duplicate
error" message.
A simple solution must be to change all the values in the ID column.
The table now:
id | name
1 | Foo
2 | Bar
etc...
Can I add the numbers "20" for every rows? So the result will be:
id | name
201 | Foo
202 | Bar
etc...
Thanks!