Those people already Spock members (including myself) still can be invited?

I was recently inviting people from my Google Address-Book, and few of those people told me they are already on Spock, with the same e-mail, and we are already connected!

I maybe didn't check carefully who did I invite, since it was a list of my good friends, but I was sure Spock will check and NOT invite those already Members and my trusted contacts.

so I tried it over myself- just added to a list of contacts my own e-mail address, and invited that my Google Contact (myself) to Spock. So what? I've got an invite to e-mail, and the text was that me is inviting me. I came back to my profile to check e-mail list- and yes, my mail was there of course.

So I think there is a bug on Spock and believe me people are not happy to be invited few more times by the same contacts, when they are already Spock Members.