BC30554: masterpage is ambiguous

I did not get this error on my dev machine. I did not get this compilation error in the staging site. I got this error in the produciton site.

Resolution: There was another file called masterpage2.aspx that was using the same namespace masterpage. It looked like a test file or for some reason a blank masterpage file was renamed this. Removed the masterpage2.aspx file , did a build and it worked fine.

Accessing masterpage objects from child page

I had a project where I had to pass in the hospital code to the link button that was at the top of the each page . The top section of the each page was a masterpage.

I added a property called SetHospitalCode on the masterpage as follows

Public m_HosCode As String
    Public Property SetHospitalCode() As String
        Get
            Return m_HosCode
        End Get

        Set(ByVal value As String)
            m_HosCode = value
        End Set

    End Property

--------
Protected Sub DashBoard_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles DashBoard.Click
      
   If m_HosCode Is Nothing Then
            Response.Redirect("DashBoard.aspx")
    Else
           Response.Redirect("DashBoard.aspx?H=" + m_HosCode.ToString())
   End If
End Sub

I set the property from the each child page as follows
Dim getMaster As MasterPage
 getMaster.SetHospitalCode =  hospitalcode 

where hospitalcode is the new value of the hospital from each page.
DashBoard is the ID of the linkbutton