Usually, you would not need to use both of these in the same sentence.
Please and kindly are both used to be more polite to other people. Having them together would only make sense if you really wanted to emphasize how important it was to be polite. You could be handling a situation in which you really do not want the other person to take offense.
Or, you could just honestly feel that the other person would not listen to you if you tried to be more forceful. Either way, only use them together when you really need to try to be extra polite.
- Would you please kindly close the door behind you after you leave?
- Could you please remember to bring the rental car back by noon, and kindly remember to have the receipt with you?
Note that, in 99% of cases, it would be polite enough just to use one or the other of these words, such as in these examples:
- Would you please close the door behind you after you leave?
- Would you kindly close the door behind you after you leave?
- Could you please remember to bring the rental car back by noon?
