Sending two parcels out but only one arrives

A question about : Sending two parcels out but only one arrives

... and then the other parcel arrives later (ha! you thought it was going to be a lost mail thread, didn't you?!)

Genuine query, just wondering what goes on at the royal mail that would make two parcels or letters, posted at the exact same time, at the exact same post office, going to the exact same destination that would result in them both not being delivered at the same time? It's not a massive problem, but buyers get nervous when one turns up and then has to wait a couple of days for the other one to show up.

Best answers:

• For the reasons given in the OP.
• I don't think I've ever used any company that had more than one parcels in a consignment that arrived at the same time.
• I've known cases where DPD had one parcel to an address delivered in the morning, then from the same van the other parcel delivered to the address in the afternoon! Dodgy software to plan that methinks.
• Some of the "packets" of information you send via the web, possibly posts on this forum are sent via different servers and switches (different IP addresses) to reach their final destination. It's the same with some other kinds of "network".