remove duplicate ArgumentNullException

Co-authored-by: Genevieve Warren <[email protected]>

Author: trivalik

xml/System.Windows/Clipboard.xml

@@ -875,7 +875,9 @@
         <exception cref="T:System.Runtime.InteropServices.ExternalException">The Clipboard could not be cleared. This typically occurs when the Clipboard is being used by another process.</exception>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="format" /> is <see langword="String.Empty" />.</exception>
-        <exception cref="T:System.ArgumentNullException">
+
+-or-
+
           <paramref name="format" /> or <paramref name="data" /> is <see langword="null" />.</exception>
         <altmember cref="M:System.Windows.Clipboard.ContainsData(System.String)" />
         <altmember cref="M:System.Windows.Clipboard.GetData(System.String)" />