Sooo, I'll share my opinion. I've seen this topic come up with using what are promoted as strips compatible for AT2, like Petsure. I personally don't know that I'd use any others strips for the meter in hand but the strips that it is made for. As you have noted, you have discrepancies in test results, perhaps to the point now where you can't trust the reading(s) you are getting. Not good.
Some people do just fine using strips that claim to be compatible, and some people use strips that look like they are the same as AT2 strips (but manufactured by a different company), but the way I see it, if I can't trust the readings, and have to use multiple strips, and still can't be sure, then time to either go back to using AT2 strips in the AT2 meter, or switch to a human meter, which is easier on the pocket book

. Plus the reference ranges and info here on FDMB, regardless of the insulin, are based on readings with a human meter, so less confusing for you. Just my 2 Canadian cents.