Creating sheets with the same names

[Anonymous]

Hello!
I'm trying to create some ViewSheets:

string pn = projectNumberTextbox.Text;
string sn = sheetNumberTextbox.Text;
int n = Convert.ToInt32(sheetCountTextbox.Text);

using(Transaction tx = new Transaction(doc))
{
    tx.Start("Create Sheets");
    for (int i = 0; i < n; i++)
    {
        FilteredElementCollector fec = new FilteredElementCollector(doc);
        fec.OfCategory(BuiltInCategory.OST_TitleBlocks);
        fec.WhereElementIsElementType();
        ElementId tbId = fec.FirstElementId();

        string shNumber = pn + '-' + sn + '-' + (n+1).ToString() + ' ' + '-' + ' ';
        string shName = "Construction drawings";

        ViewSheet vs = ViewSheet.Create(doc, tbId);
        vs.SheetNumber = shNumber;
        vs.Name = shName;
    }
    tx.Commit();
}

but at the vs.Name = shName; I get an error: Autodesk.Revit.Exceptions.ArgumentException: 'Name must be unique. Parameter name: name'.
Why is it so and how can I create some sheets with the same names and different numbers?
I would be grateful for answer.

[RPTHOMAS108]

Technically speaking in the UI you can duplicate the sheet name but not the sheet number: SHEET_NUMBER (-1007401).

The property ViewSheet.Name is derived from View.Name and ordinarily for views you can't duplicate names. Try instead changing the equivalent parameter:

SHEET_NAME (-1007400) which is not exactly the same as VIEW_NAME (-1005112).

I'm guessing class logic is mistaken somehow in trying to change wrong one or more likely falsely checks it is wrong because it generally is (except for sheets).

[Anonymous]

Omg, my stupid mistake. Instead of  string shNumber = pn + '-' + sn + '-' + (n+1).ToString() + ' ';

it must be  string shNumber = pn + '-' + sn + '-' + (i+1).ToString() + ' ';
Thank you for answer! It works!

for (int i = 0; i < n; i++)
{
    ViewSheet vs = ViewSheet.Create(doc, ElementId.InvalidElementId);
    vs.LookupParameter("Drawing number").Set(sn);
    string shNumber = pn + '-' + sn + '-' + (i+1).ToString() + ' ';
    vs.LookupParameter("Sheet Number").Set(shNumber);
    string shName = "Construction drawings";
    vs.LookupParameter("Sheet Name").Set(shName); 
}

[RPTHOMAS108]

On English language Revit there are two parameters with name 'Sheet Number'

SHEET_NUMBER (-1007401)

VIEWER_SHEET_NUMBER (-1006601)

So it is always better to use the built-in parameter enum values for BIPs rather than using .LookupParameter.