So, it is not considered as abuse for the forum if you use different accounts for different campaigns and use your real address or a campaign which has no states about only one user can join each person?
If a campaign states that one account per user can join the campaign then its very clear that joining with multiple accounts owned by the same person into that specific campaign will lead to a abuse if caught. This will be followed up with a removal of all the alt accounts on the campaign linked to that account and a red paint on those accounts for attempting to abuse that campaign funds.
Those who do such things to abuse really need to find a real meaning of their life. Abusing a campaign is the lowest level of "theft" you can do for a team who are giving you the opportunity to earn some coins.