Of course. A lot of times if you're switching dog foods (brand/type/etc) this is a good way to gradually introduce the dog to the new food so it doesn't upset his stomach and give him diarrea
Yep, easy to do. I used to do it in Kodiak with 2 protein sources as the feed store didn't always have the one I wanted, so I fed both so if they ran out and the barge wasn't due in anytime soon, I could easily switch to the other protein source at the last minute with no issues. Then I just started buying several months at a time and calling to make sure they had more when I was opening the 2nd to last bag and it would give me 2 bags worth of time to wait the barge to arrive.