Why do IRQs in /var/log/dmesg sometimes differ to those in /proc/interrupts?

Issue

Why are interface IRQs in /var/log/dmesg different to those specified in /proc/interrupts for the same interface?

For example, /var/log/dmesg may show something such as the following for eth0:

eth0: Broadcom NetXtreme II BCM5708 1000Base-T (B2) PCI-X 64-bit 133MHz found at mem <address>, IRQ 169, node addr <address>

Whereas, /proc/interrupts may report eth0 as follows:

62:       3203          0          0          0          0         0        PCI-MSI  eth0