I assume that these painted figures are repainted from time to time, and if you compare the figures that guard the two ancestral halls, you will see that those guarding the Hau Ku Shek Ancestral Hall appear to have been repainted quite recently, but all the various elements of the designs, from the oddly effeminate gesture of the hands not holding a weapon to the details of the costumes, are replicated in both cases, albeit with a degree of artistic licence involved, particularly in the faces.
This leads me to assume that a template exists for painting door gods on wooden doors, and that both painters followed it. I assume too that what we see today is a constantly retouched and repainted version of the work of the anonymous artist who painted the original figures. The template would also prescribe the weaponry carried, a Chinese halberd or ji and a broadsword by Yuchi Jingde, and a pole sword and a longsword by Qin Shubao.
However, if such a template ever existed, it wasn’t followed by whoever was responsible for the door gods guarding the Tin Hau temple. Only the ethnicity of the guards (Qin Shubao was obviously Han Chinese, while Yuchi Jingde appears to have been of Turkic origin—and the name isn’t Chinese) and the weapons they hold are the same. But the temple version of Yuchi Jingde is vastly more fearsome than his counterparts at the two ancestral halls, and the stance of Qin Shubao is more confrontational.
Finally, here is the cheap commercial version. The two posters are mirror images of each other; the only differences are in the overprinted facial hair. However, such posters are at least as effective as the elaborately painted door gods guarding temples and ancestral halls. And at least as effective as Janus, the Roman god of doorways and entrances, after whom next month is named. Janus is said to have had two heads, allowing him to look both ways at once, but he is unlikely to have done a better protection job than Yuchi Jingde and Qin Shubao, who have tirelessly been guarding Chinese homes from evil spirits and the harbingers of bad luck for almost 1,400 years and seem as popular as ever.
I will conclude with a traditional Cantonese salutation, appropriate at the change of years: lung ma ching san (may you have the strength of a dragon or horse).