I have a strange occurrence I dont understand.

I have an old wallet.dat file I am scanning all my old usb drives.

I loaded it into a bitcoin core wallet on 2 different machines running the same version of bitcoin core.

The weird thing. On machine 1 I see different receive addresses to that on machine 2.
On one machine I can see the wallet has received coins to an address starting with 3
But that is not even showing up when I click receiving addresses?
How can that be possible?

Also when I click generate new receiving addresses 5x and got 5 new addresses on each machine.
Only 1 of those 5 matched. ?

This seems weird because I was expecting these wallets to generate addresses that matched in the same order?
Is this not how it should work?

I was under the impression bitcoin core knows the next address to be generated even if it is offline?
Is one a rogue wallet generating rogue addresses it should not generate?

Electrum generates the exact same addresses in the exact same order if run on 2 different machines?
Does core not make them in order?

How to see every single address that a core wallet currently controls or has had some action?

Thanks for any explanation of this.