Unless someone leaves their name by their comment you cant tell.
Otherwise you get people repping to say thanks for the rep etc lol and that kinda defeats the purpose
On another forum I'm on you can see rep details on the user CP page (this forum must be a different build or have different options installed) so I assumed it was the same on this one.
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I always leave my name when I give a rep, like Judi I don't want or expect to be repped back because of it.
If you look in your User CP on top of the page on the Blue Bar you will see the comments left behind, but not the names of those who repped you unless they wish to leave a name.
They also have a feature to ensure friends don't continually give each other rep, you have to give at least 5 other people rep before you can give the same person rep again.
Keep up the great work and thanks for the info.
Minimins has that too you have to rep 10 people before you can rep someone again