Is GetHashCode for a file unique?

I'm using the following example to get the hash code for a file.  Is this hash code unique or could there be instances of overlapping?  If it's the later (instance of overlapping) help me understand how it occurs or if it's a rarity.

        OpenFileDialog1.FileName = ""

        If OpenFileDialog1.FileName = "" Then Exit Sub

        Dim File_Stream As New System.IO.StreamReader(OpenFileDialog1.FileName)
        Dim File_Hash As Integer = File_Stream.ReadToEnd().GetHashCode()

        RichTextBox1.Text = File_Hash

        File_Stream = Nothing
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aikimarkConnect With a Mentor Commented:
it is a rarity, but collisions can occur.  It only returns a 32-bit value, so there are only 4+ billion unique hash values.
IUFITSAuthor Commented:
Thanks for the answer.
Thanks for the points.  Glad I could help.

A much better hash alternative woulld be SHA-2/SHA160, SHA256, SHA1024.

MD5 is ok for non-sensitive applications, but NIST has put it on a "don't use for criticatl applications" list.
IUFITSAuthor Commented:
Very good, thanks for the additonal info!  :)  I'll keep that in mind.
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