Yes and NO: Yes for sure there is no official leak on that sensitive info, but since nothing hints to this - esp. not the number of J-20s spotted - the absence of a proof for one theory is not a proof the contrary.
... and No, simpyl NOT. There is surely a lot of chatter but also on green men on mars but there is o far not a single hint that there are two production lines already running. Even if You think the comparison to the J-10 production rate might be mute, that type is already needed since years and the rate hasn't been increased dramatically over the years. So why - esp. since we don't see that many J-20's like You predict - should it be such an inredible increase right now?
There are plent of rumors about CAC build new factory to setup 2 or even more production line of J-20, and it even going to big news site like sohu, 163 and xilu, with pictures of the factory ( I cannot paste link in this fucked up BBS).
If you can read Chinese, you can know alot of more information there, simply do a baidu search with "两条生产线 J-20" as the keywords ("two production line J-20), will return such results.
And even the joker pinkov (who is a famous China naysayer) suspect that there are at least two production line of J-20 is under construction and thats last year's news in his last year's issues, based on satellite photos he got.
China now build weapons at an accerelating rate, not just because China have invest more and more in defence, but also because, the rate of production years before are actually the abnormal one:
In Chinese, it called "小步快跑", because at that time the best Chinese military industry could offer were somehow out-dated by the US standard, so what the PLA should do with them? they place very small order for each iteration of the weapons and ask the industry to keep improving them iteration by iteration.
But when PLA consider the military industry can offer weapons on peer with the US, they will place large order.
Thats why they only order 2-4 052B and 052C destoryers but could order 40+ 052D destoryers and 20+ 055 destoryers and 6+ air carriers and super carriers, the same can be said about J-20.
So dont jump to your conclusion too quick.