DOC: typo (pandas-dev#16733)

Author: gepcel

doc/source/io.rst

@@ -3407,7 +3407,7 @@ Fixed Format
    This was prior to 0.13.0 the ``Storer`` format.
 
 The examples above show storing using ``put``, which write the HDF5 to ``PyTables`` in a fixed array format, called
-the ``fixed`` format. These types of stores are are **not** appendable once written (though you can simply
+the ``fixed`` format. These types of stores are **not** appendable once written (though you can simply
 remove them and rewrite). Nor are they **queryable**; they must be
 retrieved in their entirety. They also do not support dataframes with non-unique column names.
 The ``fixed`` format stores offer very fast writing and slightly faster reading than ``table`` stores.