I'm not really convinced that this is an interesting feature. People tend to choose store brands for a myriad of reasons, and stores tend to differentiate them

I'm not really convinced that this is an interesting feature. People tend to choose store brands for a myriad of reasons, and stores tend to differentiate themselves based on those market divisions. Paying a premium to get a single delivery with items from both (which is something that has a lot of logistical issues) doesn't seem like something with substantive draw.