In 4.2.2 (and now also in 4.2.4), if I create a second host-only adapter and try to set the IP address to 192.168.x.y then VirtualBox ignores me. When I reboot the machine, there is a two-minute delay and I find that the adapter has been given an APIPA address that I cannot change. Equally, if I select the adapter in Windows' Control Panel (the host is Server 2008 R2) and try to change IPv4 settings there, I can type in the values but the adapter remains resolutely stuck on the 169.254.x.y. address.
(I believe APIPA is not recommended for multi-homed hosts, so there's some irony in this bug only kicking in for the second adapter. )
This all worked in every version up to 4.2.0 (which I have stuck with for now).