Retirement tax questions

Thanks Vanessa and Ernie, very helpful answers.  One more detailed question.  

 

My wife and I are retied with two sources of income:  my pension and a monthly distribution from my 401K.  Our monthly income from each is equal to the other, i.e., each contributes 50% of my monthly income.

 

My current withholding is too low, so I am submitting a new W-4P to the pension provider.  If I include the income from my 401K on line 2(b)(ii) will withholding on my pension be doubled to accommodate the 401K distributions (from which income tax is already withheld)?

 

Or should I ignore line 2(b)(ii) and simply complete a new W4-P (or whatever) for my 401K distributions as well?