Type 075 is already a duplication, with Type 382 having the S/C combo, and the new "Type 383" having the S/X combo, assuming the rumors are correct (I still have certain doubts, pieces don't align perfectly) about the second radar.
Its not difficult to create variations of this radar however, to create either an S/S or an X/X for different purposes.
The primary reason for going with a rotating radar is to save money as you only have a single or dual face versus four faces. The radar configuration is going to be shaped by how much you are willing to spend on the ship. A four faced X-band is ideal, but it maybe deemed too costly. I don't know how deep the PLAN's stomach for spending per 054B unit will be. You are confronted with the sliding bar of cost, but you don't know where the 054B and even the 052E maybe placed along these bars. I don't think the PLAN is willing to spend that much on a 054B frigate compared to other nations, where the frigate is their top end and they are more willing to spend on that, as opposed to the PLAN which already has other top end ships.