Duplicate form ID numbers in database

My form connects to an Access database. When the employee enters their employee ID number and exits that field, the form searches thru the FileName database column to find the largest number. It then adds 1 to that number (maxID), makes the rawValue of the FileName field on the form the same number, adds a new record and updates the database with the new information. It works great with one exception. I keep getting duplicate numbers in the database but it only happens occassionally. I can't figure out why it happens. When it does occurr, both forms were created within a couple minutes of each other. Please inspect my script and see if I have something wrong.

if (Subform1.FileName.rawValue == null || Subform1.FileName.rawValue == ""){
var nMaxID =0;
//Reset DB to first record
var oDB = xfa.sourceSet.DataConnection1;
try{
oDB.first();
}
catch(e){
oDB.open();
oDB.first();
}
//walk thru all records to find latest file ID
while(!oDB.isEOF()){
if(xfa.record.DataConnection1.FileName.value > nMaxID)
var vValue = xfa.record.DataConnection1.FileName.value;  nMaxID = Number(vValue);
oDB.next();
}
oDB.addNew();
Subform1.FileName.rawValue = (nMaxID + 1);
Hide1.FileName1.rawValue = Subform1.FileName.rawValue;
oDB.update();
Hide1.EmployeeNo.rawValue = Subform1.EmployeeNo.formattedValue;
Hide1.Originator.rawValue = Subform1.Originator.rawValue;
Subform11.FileName.rawValue = Subform1.FileName.formattedValue;
this.resolveNode("OrderDate").rawValue = util.printd("yyyy-mm-dd", new Date());
Hide1.DateTimeExitedEmpNumber.rawValue = Subform4.DateTimeExitedEmpNumber.rawValue;
oDB.update();
oDB.close();
}
else{
//HEADER SECTION
//Reset DB to first Record
var oDB = xfa.sourceSet.DataConnection1;
oDB.open();
try{
oDB.first();
}catch(e){
oDB.open();
oDB.first();
}
//Walk thru all records until test value is matched
var oFile = Subform1.FileName.formattedValue;
var bFound = false;
while(!oDB.isEOF()){
if(xfa.record.DataConnection1.FileName.value == oFile){
bFound = true;
break;
}
oDB.next();
}
if(bFound){
}
Hide1.EmployeeNo.rawValue = Subform1.EmployeeNo.formattedValue;
Hide1.Originator.rawValue = Subform1.Originator.rawValue;
Subform1.FileName.rawValue = Subform1.FileName.rawValue;
oDB.update();
oDB.close();
}