Removed duplicated words in in comments and docs.

Python/pystrtod.c

@@ -325,7 +325,7 @@ _PyOS_ascii_strtod(const char *nptr, char **endptr)
 
    On overflow (e.g., when trying to convert '1e500' on an IEEE 754 machine),
    if overflow_exception is NULL then +-Py_HUGE_VAL is returned, and no Python
-   exception is raised.  Otherwise, overflow_exception should point to a
+   exception is raised.  Otherwise, overflow_exception should point to
    a Python exception, this exception will be raised, -1.0 will be returned,
    and *endptr will point just past the end of the converted value.
 

Python/random.c

@@ -225,7 +225,7 @@ lcg_urandom(unsigned int x0, unsigned char *buffer, size_t size)
 }
 
 /* Fill buffer with size pseudo-random bytes from the operating system random
-   number generator (RNG). It is suitable for for most cryptographic purposes
+   number generator (RNG). It is suitable for most cryptographic purposes
    except long living private keys for asymmetric encryption.
 
    Return 0 on success, raise an exception and return -1 on error. */

Python/thread.c

@@ -221,7 +221,7 @@ find_key(int set_value, int key, void *value)
             goto Done;
         }
         /* Sanity check.  These states should never happen but if
-         * they do we must abort.  Otherwise we'll end up spinning in
+         * they do we must abort.  Otherwise we'll end up spinning
          * in a tight loop with the lock held.  A similar check is done
          * in pystate.c tstate_delete_common().  */
         if (p == prev_p)