I wouldn't say imitate, I mean Britney Spears is INSPIRED by Janet Jackson she has said so many times. She has of all the performers used Janet's style the most. Do you remember the YDMC tour when during the dance break during "Crazy" Britney stop and say "Is that the end?". That was from a Janet Jackson video where she did the exact same thing. "Stronger" is more reminiscent to me of "Pleasure Principle" because of Britney dancing by herself and alone like Janet is PP. But like I said I wouldn't say imitate. Like Usher is inspired by Michael Jackson, I wouldn't say imitate.

Hope I helped.
-Ricky