Obviously, yes. A safe bet here is that it hit a rock or something, or a primer was proud of its pocket and took the blow.
I consider it likely the second one was probably sympathetic, not necessarily a second ignition. I assume they were next to each other in the box?
Apparently you did not have to look very far for the bullets. Is it the lighting , or are those 2 dissimilar bullets? If so , how did that come about?
i may or may not have dun that to lol.We used to set off .22 lr cases after we'd pull the bullets to burn the powder for fun, by repeatedly throwing them at the ground and always got em to pop after a while. And tried it with 9mm primed empty cases we found in middle school. So yes it can happen very rarely with out deliberately trying.