WordPress MU

2 weeks ago I migrated to a new server and everythign seemed to go smoothly. Now I noticed that when I click i.e. onto a comments table, i.e. wp_1_comments I get the following warning using phpmyadmin:

More than one INDEX key was created for column "comment_approved"

these are the existing indexes:

Indexes:
Documentation    Keyname  	Type  	Cardinality  	Action  	Field
PRIMARY 	PRIMARY 	0  	Edit 	Drop 	comment_ID
comment_approved 	INDEX 	None  	Edit 	Drop 	comment_approved
comment_post_ID 	INDEX 	None  	Edit 	Drop 	comment_post_ID
comment_approved_date_gmt 	INDEX 	None  	Edit 	Drop 	comment_approved
comment_date_gmt
comment_date_gmt 	INDEX 	None  	Edit 	Drop 	comment_date_gmt

the problem is that all blogs I create from now on, have this problem :-( any hints?

just found the standard wordpress DB schema: http://codex.wordpress.org/Database_Description#Table:_wp_comments and the wpmu one (partially) http://codex.wordpress.org/WPMU_Database_Description

does this now mean there is no problem? is it a false warning by phpmyadmin?