(bottom are busses, and their ids, and above are IOAPIC IRQs src, dst, modes, bus id)
Here's the IOAPIC irq routing in my Bochs, nothing special about it:

QEMU, also nothing special:

And here's VMWare, looks crazy:

Why are there 2 IRQ0 sources from the ISA bus?
Does that mean they're shared?
How would I know for example, which one of them I'm looking for when mapping them in IOAPIC, do I redirect both to the same handler?
What other device can possibly be IRQ0 on the ISA bus other than the PIT?
Thanks.