Tbh... looking at the China’s aircraft carrier program so far I don’t think a second type 003 is likely to be currently under construction... and to be frank the original time line/frame of 6 aircraft carriers, 2 STOBAR and 4 CATOBAR, being built by China, if memory serves but I might be wrong on the years, by 2030/2035 was also somewhat ambitious and speculative at the time but still possible.
First of all, this is not a knock on China’s ability to construct aircraft carrier but merely an analysis based on the current progress of the carrier program. I would fully expect that the carrier construction program to accelerate after the first type 003 is commissioned, tested and provide a positive result, while the Liaoning provided a lot of initial and general operational experience, the construction of Shandong provided a lot of construction, structural as well as on going general operational experience, the construction and performance of Type 003 would be the measuring stick for PLAN future carriers and I would expect the PLAN to want to work out any kinks before committing to more. So I believe once the type 003 has been fully tested operationally we would then likely see the acceleration of the program at that point, for example the second type 003 if there will be a second or possibly simultaneous construction of a further iterations from type 003.
For cases of building ships in 2s... there would have been enough transferable experience from the predecessors of those classes of ships to make reasonable deductions of the systems and performance of the new class... but an aircraft carrier is still relatively new experience, with a new design as well and quite a significant investment of time and resources... especially now that there are unfamiliar systems to be tested and all that can be done with one test bed first, rather then committing such resources on multiple ships like what the Americans did with the Zumwalts only to find out the initial prediction were wrong. I just don’t think the PLAN would commit such resources until they have a reasonable assurance of the design or systems, which tests on the type 003 will provide for future reference.