Republican observers were not able to check double voting or fraudulent voting

Elizabeth Preate Havey, an attorney and a resident of Montgomery County and the chair of the Montgomery County Republican Committee, Pennsylvania State Senate Hearing, Nov 25

For over 200,000 mail-in ballots in Montgomery County, republican observers were not able to check to see if a voter voted twice or if a voter deceased. With the removal of signature being checked for existing voters, there was no way to protect against someone fraudulently voting for a registered voter.