I have about 4 of each camera and I feel confident in saying that the 5442 is better in every respect except that it would require two of them. The low-light performance of the
IPC-T5442T-ZE is dramatically better with the 1/1.8" sensor. It might not matter if using the infrared LEDs, but those are HORRIBLE on the dual-lens camera because of the domes. The domes also make it impossible to see anything if exposed to rain, and then often get dirt on them (from dust + water) that must be cleaned. The cameras are slow because you only have one processor to handle two different streams, and in fact the original version didn't even support the same IVS functionality on both streams because it couldn't. The IPC-T5442T-ZE also supports zooming in, rather than trying to replace a lens to have a different focal length on a dual-lens camera. Let's also not forget that the 5442 supports using any modern browser, while the dual-lens cameras are stuck in the dark ages and require IE or a plug-in that still doesn't really work. IMHO, that's insulting to all users and almost negligent on the part of Dahua.
As I said, I own 4 of them, but I generally don't like them. So why don't I replace them? Because they are convenient and there are locations where I either cannot or will not mount two separate cameras. I realize that "cannot" sounds too absolute, because it's almost always possible to split even a single wire and even use a stronger PoE injector if you're at some limit (e.g. I have three cameras on one run, including a PTZ, so even a 30W injector isn't enough). Having said that, Dahua doesn't offer mounts that are intended for mounting two cameras together, and often the aesthetic of two separate cameras would not be acceptable to various people (from wives to businesses).
The new dual-lens, full-color cameras have SUCH a better form factor that I wanted to upgrade to use them, BUT they don't use infrared illuminators and I don't want visible white light on all the time at night.
So I own 4 of the current dual-lens cameras and I wouldn't change my decision at the time, but they frustrate me a lot. They serve a purpose, but unfortunately come with compromises. You need to decide whether those compromises are worth it to you for the convenience. There is no one "right" answer for everyone, but if you don't mind the aesthetic of 2 T5442T-ZE cameras, or the cost of two separate cameras, or the logistics of supporting two separate cameras, I'm absolutely confident the image quality and function of two cameras will be better.
