Duplicate add-ons in IE9

Going to 'Manage add-ons' in IE9 due to a possible problem, I noticed that there were duplicate entries in some cases - for example Live Mail & Messenger, Do Not Track Me, Quicktime and Java 10.60.2
Would it be OK to disable one instance and leave the other enabled or would this cause a problem?
Better, is it possible to remove one and leave the other behind?

Also there are 4 instances of Java - SSV Helper, 2SSV Helper, 10.60.2 (twice) and 1.7.0_05
Are all these required or can some be disabled or removed?

Thanks for any help.

My Computer

System One

  • Manufacturer/Model
    emachines E720