'Duration normal' is used for units. 'Duration Hero' is used for heroes. For example if you see Storm bolt ability what is Human hero ability it stuns units longer than heroes. If ability is used by or ability target is hero 'Duration hero' is used and when unit 'Duration normal' is used.
Finally finding about some of the bots that are flooding the users online - bytespider apparently is a huge offender here - ignores robots.txt and comes in from a ton of different IPs
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.