It may be unusual for the industry, but we've been burned by China in the past. Often you'll have to rip some components off to find the part number on the chip. If we don't have to destroy it we certainly won't.
Most companies don't advertise the sensors or DSPs, and it's a very EASY way to say that your camera is the same as our camera, only cheaper! Except its really just the same housing and not the same camera at all.
While OV was still Japanese we used that as a selling point (China bought them). We had found that most Americans don't come out and ask about the chipsets and sensors, but if you take the time to educate them then they start caring a little more. Everything is marketing I guess...
We have to specifically ask the manufacturers for the Sensor & DSP models, and we do it for every camera. We list the DSP & Sensor on every model that we can confirm. You'll see bullet points & specs that say "1.3MP Aptina AR0130 Sensor & Ambarella A5S DSP" or "4MP 1/3” Progressive Scan CMOS Omniview OV4689 " This allows the consumer a little more power when comparing quotes.
This starts to get very important when considering home automation, because the A5S DSP worked with Control 4 and all the others, but the S2LM did not. This causes problems when its the same "model" of camera, but a different DSP. We ran into this issue last year.
As for how often we check it; it depends, if we notice something is different or off then we definitely check it. If nothing has changed within 12 months we trust the manufacturer. However, the industry releases new products before your old container has even arrived... so we're rarely selling the same model for more than 12 months at a time.
We have seen minor variances that don't matter as well, maybe a capacitor has changed, or a resistor has moved, things like that don't exactly matter to the image being produced. But we believe your DSP & Sensor matter quite a bit. 4MP doesn't mean a better image, and it's a shame that the industry doesn't know this.
Ask a professional photographer if a 36MP camera is better than a 24MP camera... you can't answer that question based solely on mega pixels. Plenty of Ambarella/Sony 2MP cameras produce a better image than an OV/HiSilicon 4MP camera, but does the consumer really care? 4 is bigger than 2!
I honestly would like to see more transparency in this industry. Hopefully all of these discussions on IPVM can help with that goal.