The person that told you this is full of hogwash. Being signed with the same ink provides no evidence that two people were together at the same time (unless th

The person that told you this is full of hogwash. Being signed with the same ink provides no evidence that two people were together at the same time (unless the ink is extremely rare and hard to procure), and you cannot tell if two signatures were done with the exact same pen. Two people can sign with the same model of pen within days of each other and you can't tell the difference after a few days- and most legal disputes are going to occur more than a few days after signing. Being signed with two different pens also doesn't suggest anything other than the two signatories used different pens. If you want legally admissible proof that two people signed a document together then you need a notary. Of course a notary could be corrupted, but the courts are much less concerned about that than they are about the chance that two people both own a Pilot G2 in black.