Have not had that problem with AVID. I suppose a computer entry error could be made by any of the companies, I think this serves as a suggestion to us all to lookup our own animals to see it they are in fact in the data base.
As Wanda said, most of the unregistered chips we find are still registered as sold to the rescue. We have a cat this weekend (probably ran from the fireworks) with a Home Again chip registered to the city of Chicago. We have to wait till Monday to contact their agency to find out who adopted the cat.
Hope this all gets straightened out.
RE the different chips, it's not just Banfield, AVID, Home Again. I'm currently working with a client trying to get their dog legally transported to Greece. The EU requires a chip that is not commonly used in the US and the owner has to get it re-chipped with a special chip or carry a scanner that can read the chip that is implanted. AVID makes the EU compatible chip, but it's a pain keep multiple kinds and have the appropriate record keeping. Reminds me of Beta vs VHS with video recorders.
Doug, DVM