I didn’t really think they actually covered that plot point well.
The biggest problem iirc is a duplicated loaf of bread has the same expiration date as the original, so you can’t actually make bread last forever with duplication without it getting moldy. Preservation charms wear off the same as muggle preservatives do.
But I don’t see why dried or smoked food couldn’t be duplicated for months or years. The biggest threat would be scurvy at that point.