User blog comment:Callofduty4/Black Ops II impressions on Zombies, new campaign level, and more!/@comment-68.187.96.53-20121013234235/@comment-1854594-20121014005750

You can only have one of each category of item at a time (except I believe attachments) unless you use a Wild Card to get and extra something (like a second perk) This means getting more then 1 perk in a category makes you sacrifice one of your points.