What state did this occur in?
When this happens, we are generally encouraged to go with the most recent order.
When someone shows the police a restraining order - or they have a record of a valid order on file, we are required to enforce the order. It is not the position of the police to decide if a judge was in error or not. Absent any complete and true knowledge that the order was in error, we are generally required to enforce it.
Hire an attorney and go after the other party for falsely complaining about you. See if the DA will file charges against the other party for filing false police reports.
However, it is often hard to PROVE that a report was knowingly and intentionally false. Unless the other party said they spoke to you and you can prove that you were somewhere else, there is ample room for error ... a car similar to yours could have driven by, etc.
In this case they are there to enforce the laws of your unmentioned state.
Maybe. But nothing precludes you from asking the police about the possibility of charges against the other party or from hiring an attorney.
A Nor Cal Police Sergeant
"Make mine a double mocha ...
... and a croissant!"
Walk humbly with your God
-- Courageous, by Casting Crowns