The best part will be the launch of two 052D's:
1) only to launch two 052D's but flooded full dry dock;
2) to build two more ships at current 052D's spots, and launch all four ships at same time.
I think what is more likely, is that after the launch of the two 055s (flooding half the drydock), the divider in the drydock will be lifted, the two current 052Ds will be shifted to where the 055s were built, the divider will be put back into the drydock, and then two more ships (likely 055s) will be built where the two 052Ds currently are.
The two 052Ds will then be launched with the divider in place (aka flooding half the drydock).
I can't see four ships being launched at the same time, because that means half of the drydock won't be able to be used for assembling ships and it would be a waste of time and space.