Good points.Ah yes that's the only one I had with that issue. I had more issues with that one hatch I did. No issues after even with breeding those that had the issues. None that have come from those have had issues. I'm still keeping any eye out on each hatch.
Two in one order seams weird but could just be a correlation and not something to worry about. All we can do from that point is breed a few generations our selves and see if it pops up. If not then it's a one off. If it shows up then it's a problem to cull for. I might send an email to them to look out for the issue in their own stock or chicks they hatch from their breeders.
I didn't do any breeding with the ones I had, and it didn't occur to me to tell the hatchery because I didn't care enough to demand a refund, but I should keep those things in mind if I ever have a similar situation in the future.