You've been invited to collaborate on code emails

Hello,
I create a group for my organization and invited 4 people. Since then, a number of other people in my org have been invited (not be me or anyone I invited) and I'd like to know what is happening. Just today, members of the org received invitation emails...which I did not initiate.

I invited the first 4 users listed in the screenshot. Don't know how the other two got invited.

Thanks,
Eric