Yes and it is not critical in my case.

Let me explain once more:
(A) First, I use only internal watch dog and microcontroller hangs (approximately once a day).
(B) Next, I use external Watch Dog (DS1232) and now system works without hanging up.

Only difference between A and B is:
In hardware: I disconnect Strobe Input from ALE and I connect it to free I/O line.
In software: a cyclic triggering of Strobe Input and canceling internal Watch Dog

Therefore system is working correctly with external WD now.
Previously system hangs with internal WD.