Salaam all,
I've been thinking about this rather weird question regarding Sunnah/Nafilah prayers for quite a while now, and I haven't been able to find an answer on any of the major Marjas' websites. I'll illustrate the question with a timely example: In the first 10 days of Dhu al-Hijjah, we have a specific mustahabb salat of 2 rakats, to be recited after Maghrib. Now, my question is: Should we perform this prayer IN ADDITION to the regular 4 rakats nafilah of Maghrib, making 6 rakat (3 x 2 rakat). OR, should we not do the regular 4 rakat nafilah and swap it out for this special prayer?