I am upgrading from 6.4.2 to 5.1.1.1

I've gotten past the "The following files are reporting a wrong version #" problem and then run into a few problems in the altertable steps.

When it throws an error during the upgrade.php?step=altertable it will not restart at that step. In my case Ive made it to alterstep 22 and get the following error

****
Updating step to 22 .... OK
Activating all current graemlins... FAILED
SQL Query: ALTER TABLE w3tA_Graemlins ADD INDEX active_ndx (G_Active)
Reason for failure: Duplicate key name 'active_ndx'
Upgrade Step: http://www.cmcrossroads.com/f/ubbthreads/install/upgrade.php?step=altertable

It does set the w3tX_Version variables correctly
V_Version = 6.5.1.1
V_AlterStep = 22

But if I rerun http://www.cmcrossroads.com/f/ubbthreads/install/upgrade.php?step=altertable as instructed it jumps to the next step and skips steps 22-50

Next message says
[]
Updating database to version: 6.5.1.1
If at any time this step times out you may just refresh this screen and it will continue.

Finalizing upgrade to version 6.5.1.1 .... OK

Finished updating to version 6.5.1.1. Continue to next step
[/]

But it didnt finsh added tables and columns.