zcInstallDEBUG-xx.log Can't DROP 'page_accessed'; check that column/key exists

I'm in testing mode, in a sub-directory, with plan to upgrade my Zen-Cart from 1.3.9h to 1.5.5 (03-24-2016 zip).

I checked my logs and found only this throughout testing:

[27-Mar-2016 14:59:50 America/New_York] MySQL error 1091 encountered during zc_install:
Can't DROP 'page_accessed'; check that column/key exists
ALTER TABLE admin_activity_log DROP INDEX page_accessed;
---------------


[27-Mar-2016 14:59:50 America/New_York] MySQL error 1091 encountered during zc_install:
Can't DROP 'access_date'; check that column/key exists
ALTER TABLE admin_activity_log DROP INDEX access_date;
---------------


[27-Mar-2016 14:59:50 America/New_York] MySQL error 1061 encountered during zc_install:
Duplicate key name 'idx_page_accessed_zen'
ALTER TABLE admin_activity_log ADD INDEX idx_page_accessed_zen (page_accessed);
---------------


[27-Mar-2016 14:59:50 America/New_York] MySQL error 1061 encountered during zc_install:
Duplicate key name 'idx_access_date_zen'
ALTER TABLE admin_activity_log ADD INDEX idx_access_date_zen (access_date);
---------------

mc12345678 posted the same install error on page 42 #412 in forum FEEDBACK ON BETA of v1.5.5, but I could not find further information.
Can someone tell me what, if anything, I need to/should do?

Thank you so very much!

You can ignore these for sure as it is just information that the key already exists

[27-Mar-2016 14:59:50 America/New_York] MySQL error 1091 encountered during zc_install:
Can't DROP 'page_accessed'; check that column/key exists
ALTER TABLE admin_activity_log DROP INDEX page_accessed;
---------------

[27-Mar-2016 14:59:50 America/New_York] MySQL error 1091 encountered during zc_install:
Can't DROP 'access_date'; check that column/key exists
ALTER TABLE admin_activity_log DROP INDEX access_date;

I am not so sure about the other 2???
But it appears that it was allowed and just reporting the initial error due to the last statements

ALTER TABLE admin_activity_log ADD INDEX idx_page_accessed_zen (page_accessed);

ALTER TABLE admin_activity_log ADD INDEX idx_access_date_zen (access_date);

Those 4 particular statements are just cleanups to get old schemas in sync with the new.
Nothing to worry about.

If you want, you can go into your tables and double-check that things it was trying to add or drop are already added or dropped.

Thank you Kobra & DrByte.
I'm understanding more everyday!