Description:
2 mysqlds starting up simultaneously like in mysql-test-run

they will create cluster/schema table simultaneously

a race happens for the create table - create event sequence

the mysql server that "discovers" finds that no event has been created, and will attempt
to create one, inbetween the first mysqld comes in and creates the event, create event
code from second mysqld will attempt to recoved by (wrongly) deleting the event, and
recreating it

How to repeat:
see above

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/4093

peshed to 5.1.8

Thank you for your bug report. This issue has been committed to our
source repository of that product and will be incorporated into the
next release.

If necessary, you can access the source repository and build the latest
available version, including the bugfix, yourself. More information 
about accessing the source trees is available at
    http://www.mysql.com/doc/en/Installing_source_tree.html

Additional info:

Documented bugfix in 5.1.8 changelog. Closed.