duplicated javascrip in other plugins

Hi
In settingfs od Social marketing plugins says
"My site already uses javascript from this service:" Facebook, twiter...
How do i know if any other plugin uses this javascript???

Because if i use a plugin to facilitate sharing with other social networks, simjply adding an icon fron this social networs to connect with them.

is this considered the stuff that we are talking about??

Or we are talking about something like "ultimate facebook" where i have to have an app from facebook and has to be connected with my site.

So, How do i know if i already use javascript from any of this services??

Thanks