The entire point of having an alt in most cases is to segregate the identities and provide anonymity. Trying to hide the fact that it is an alt alone is not evidence of any illicit activity.
You mean that I am allowed to use a second account to use as another official member, I can use two accounts to participate in different signature campaigns to earn decent money 
This sounds great! And when I opened a campaign management service, I could open with both accounts to increase my chances of competing with others without anyone knowing Go ahead!I was just kidding
Is that what happened though? So far all I see is evidence the accounts might be linked, not proof they are in contractual violation with any campaign manager. As you can see I already addressed this early in this thread:
I would say this constitutes pretty clear evidence of this being an alt account. I don't think any flags or ratings are appropriate at this stage. I think it would be appropriate to inform the managers of any campaigns he is involved in. If he is violating the terms of those campaigns, then a rating or a flag may be appropriate. I would like to hear the manager(s) comments on the matter.