While it is possible that Clemens did entertain the thought of
suicide more than once, the question or comment regarding Kipen's
commentary was based on his statement:

"Hardly any scholars have attempted to pin Twain down as to exactly
when in 1866 he contemplated suicide..."

Certainly scholars have long speculated and tryed to pin down the date.
The Oct. 20, 1865 "pistols or poison" letter is evidence that the
thought was in his head as early as Fall 1865.  The 3 month time line
was expanded upon by Fanning who writes it was "one day short of
the deadline he set for himself" (p. 108).