Originally posted by IPG 1.3:
Separate infractions committed or discovered at the same time are treated as separate penalties, though if the root cause is the same, only the more severe one is applied.
In your example, it's the same root cause - i.e., the same (set of) action(s) - so apply “the more severe one”.
Now - which of those is more severe? Neither, they both come with a Warning.
I would assess the one that's more specific to the action(s) - in this case, Insufficient Shuffling (which happened to include seeing cards he shouldn't have).
d:^D