Some of the scientists claim they did not sign the contract with the addendum for fees. Also, apply your judgement - this is highly unusual and my first impres

Some of the scientists claim they did not sign the contract with the addendum for fees. Also, apply your judgement - this is highly unusual and my first impression is it’s obviously a scam. If people sign contracts that are altered and a scam, should they be upheld just because someone agreed to it?